Commented on Are ordinary least squares coefficients 'linear' in the following sense.. "If I have two sets of noisy data, with same number of points in each set and measured at the same set of x positions, then carry out a polynomial least squares fits on each set of data, are the result"

Short question. Proof for $e^{\frac{1}{n+1}}-1-\frac{1}{n}\leq0$‌​. "I'm looking for a proof of $e^{\frac{1}{n+1}}-1-\frac{1}{n}\leq0$, optionally $ln(n)+\frac{1}{n+1}\leq ln(n+1)$ "

Commented on Explain that two parametrizations represent the same curve. "Task: I have the two given curve, in different intervals for t: x_1(t)=t , y_1(t)=t x_2(t)=t^5 , y_2(t)=t^5 for t ∈[-1,0] and x_1(t)=2t , y_1(t)=2t x_2(t)=16t^4 , y_2(t)=16t^4 for t ∈["

Commented on I need to find the rule between the input and output of these values. "Is anyone able to find the rule? If possible, can you explain how and what's the name of that kind of rule? Input Output 0,18 0,316 0,32 0,4536 0,353 0,4892 0,33 0,4644 0,34 "

Commented on What is this kind of cone called?. "Consider the following cone: Assume a circular base (but I don't think that's really critical to my question). Note that the line connecting the vertex of the code to the plane of the base, where t"

Commented on Area of region under 2 curves.. "Find the area of the region R enclosed by the line y=2x−1 and the parabola y^2=4x+141 Here is what I have done: Write each equation in terms of x. (x=(y+1)/2 and x=(y^2-141)/4) Find intersections: "

Short question. Tagged proof-theory. Prove or disprove: f(x) = x^2–2x+1 is monotonically increasing for real values of x>1.. "I kind of understand the premise of this problem, but I'm not sure where to begin. Any suggestions? "

Commented on Easy probability problem verification involving union and intersections.. "The following table lists the most popular U.S. convention centers.Suppose the probability given represents the likelihood that a randomly selected U.S. convention will be held at that site. Orlando:"

Short question. [Is $\mathbb{Z}[\sqrt{-7}]$ a UFD or not?](math.stackexchange.com/q/1628624). "Is $\mathbb{Z}[\sqrt{-7}]$ a UFD or not? I feel like there should be some easy example showing that it is not, but I can not think of one. "

Commented on discrete mathematic Question that i need help with please. "Determine the number of integer solutions of x1 + x2 + x3 + x4 + x5 = 32 where xi > 3 for 1 ≤ i ≤ 5. "

Short question. Prove $\lim_{n\to\infty}\frac{1}{n!}^{\frac{1}{n}}=0$. "I'm trying to prove that $$\lim_{n\to\infty}\left(\frac{1}{n!}\right)^{\frac{1}{n}}=0$$ Can anyone help me with this? "

Short question. Expectation of (X-bar)^2. "If all enumerated Xs are observations from a population with a population mu and variance sigma^2: Why is this true?(s0.wp.com/…;

Short question. find x such that 2^x-1 is divisible by 77. "Please help me develop a method for finding x such that (2^x-1) is divisible by 77 Thanks "

Commented on Stuck solving $\int \frac{1}{1+sin(x)} dx$. "I'm having trouble finding the solution to the following integral $$\int \frac{1}{1+sin(x)} dx$$ I know that the first step should be: $$\int \frac{1}{1+sin(x)} dx= \int \frac{1-sin(x)}{(1+sin(x))("

Commented on Which form do I use in this quadratic example for factoring?. "Alright, so I have the equation: x^2 + 5x = -4 To find the axis of symmetry and the zeroes (by using the quadratic formula), would I have to write it in standard form, which is x^2 + 5x + 4 = 0, or wo"

Commented on Mathematical intuition vs physical intuition. "Terrence Tao wrote about intuition in "There is more to math than rigour and proofs" in his blog what's new. My question, might seem a bit irrelevant to this stackexchange, is that how the natural in"

Commented on General Formula for Equidistant Locus of Three Points. "I need a general formula that calculates the equidistant locus of three points $(P_x,P_y)$; in terms of the coordinates of the three points $(A_x, A_y), (B_x,B_y), (C_x,C_y)$. Setting the distances e"

Title contains ??. Which form of this quadratic do i use to solve intercept and range???. "So my equation is: -2x^2 + 4x + 30 = 0 If I use this form to look at my y intercept, it will be 30. However, once I simplify it to: x^2 - 2x - 15, then my y intercept will be -15. Which one do I use?"

Short question. If $x^4 + 4^y$ is prime , then $x$ is odd and $y$ is even.. "Should I take the contrapositive of the implication and prove x^4 + 4^y$ is not a prime. "

Commented on Is this quadratic pointing up or down? how do i know?. "The equation is -2x^2 + 4x + 30 = 0 i simplified it to -2(x^2 - 2x - 15) To know if it points up, I need to look at ax^2, and if a > it is up and if a is < 0 it is down. However, which version do"

Commented on DNF simplification. "I am currently learning about propositions and logical equivalences in a mathematics course I'm taking at university. I'm having trouble understanding how to simplify DNF Formulas. I was given a truth"

Commented on Need help checking proof of generalized replacement theorem. "So the generalized replacement theorem goes as follows: Let B be a basis for a vector space V, and let S be a linearly independent subset of V. There exists a subset S1 of B such that S U S1 is a basi"

Short question. Would absorption law work for statements with neagations in them like (¬p∨¬q)∧¬p?. "Would absorption law work for statements with negation in them like (¬p∨¬q)∧¬p? "

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Commented on Finding g'(x) of the following.. "So I need help solving the following question. I tried to do it and got 5x^4sin(x^2), but the correct answer is 5x^4sin(x^10). Where did the x^10 come from? "

Short question. For this pair of equations, write s in terms of a only.. "For this pair of equations, write s in terms of a only. s=ah h=a(2+h) "

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Short question. 1995 USAMO Problems/Problem 2. "i tried to solve this problem artofproblemsolving.com/wiki/… and i want to know how he came up with this formula sqrt{m/n}. "

Commented on Jordan Canoncial Forms Question. "I need help with this question I am currently completly lost on how to even do part A. For part B and C I think we have to use J = $P^{-1}AP$ but I am not sure 100%.If someone could please provide a p"

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Short question. Semimagic square Matrix. " How to prove this? Basically I have no idea at all as how to proceed in this particular question. Please look into this. "

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Commented on Interesting sites without pull-backs. "I've seen at least a couple of sources (e.g. the nLab) that do not require the categories with which we are equipping coverages to have pull-backs. The question is simple: are there any interesting "

Commented on Let A be a 4*4 matrix with real entries and its eigen values 1,-1,2 and -2 ,then which of the following statements are true?. "If B is a matrix defined as B=A^4-5A^2+5I , where I is a 4*4 identity matrix , then 1.Determinant(A+B) =0 2.Determinant(B)=0 3.Trace(A+B)=4 From the given conditions ,I could only conclude that tra"

Short question. Calculate $ln(2)$ Without calculator using taylor series. "I have to Calculate $ln(2)$ Without calculator using taylor series. Help someone ? Thanks "

Short question. $C^{\infty}_{C}(\Omega)$ it is dense in $ W^{1,2}(\Omega)=H^1(\Omega) $ ? I know that it is dense in $H^1_{0}(\Omega).$. "$ C^{\infty}_{C}(\Omega) $ it is dense in$ W^{1,2}(\Omega) = H^1(\Omega)$ ? I know that it is dense in $H^1_{0}(\Omega) $ . "

Commented on A particle moves along the x-axis acceleration Question. "A particle moves along the x-axis, its position at time t is given by x(t)=3t/(6+8t^2), t≥0, where t is measured in seconds and x is in meters. The acceleration of the particle equals 0 at time t= "

Short question. Why is the dimension of the cohomology group $H^{d,0}(M)$ of a Calabi-Yau manifold 1?. "Can I deduce this from the fact that there is a non-vanishing $(d,0)$ form on the complex dimension $d$ Calabi-Yau manifold? "

Title contains please. Please explain, "Asymmetric is stronger than simply not symmetric".. "In some textbook I found a statment like, "Asymmetric is stronger than simply not symmetric". But as I try to perceive this statement, both appear to be same to me. For example, parentof is an asymm"

Commented on relations and equivalence classes question. "S is the set of al equivalence relations on set A = {1,2,3,4,5,6,7,8,9} in witch one of the equivalence classes is {1,3,5,7,9}. What is the size of S? I don't even know how to start... Detailed ex"

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Tagged pde, differential-equations. Tagged differential-equations but mentions "partial". Solving a system of ODE that arose in solving Burgers' equation. "Consider the Burgers' equation $$\partial_t u = \alpha u\partial_xu$$ Intend to solve this using Fourier Galerkin method. So When I convert this into $N$th Fourier partial sum, I get a system of ODE's"

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Title contains please. Short question. Can you please tell me how can i choose the value of increment and repetition here?. "I am using the given below link to calculate the jacobi polynomials, keisan.casio.com/exec/system/1180573414 enter link description here "

Commented on Check if a function is injective through derivation. "I have this equation: $$1+2^{log_3x}=x \text{ where } x \in \mathbb{R}$$ Anyone can immediately see the solution, $x=3$, but the remaining problem is to prove that $x$ is the unique solution. We can "

Short question. to calculate by the index of the element its number. "How can I specify a formula to calculate by the index of the element its number? cut-the-knot.org/do_you_know/diag.gif Thank you "

Commented on What is the most awkward quadrilateral for tiling a plane?. "In this context, all quadrilaterals are taken to be congruent, same-handed, and non-overlapping (except perhaps one-dimensionally along their boundaries), and awkward means that, however the quadrilat"

Short question. Sigma algebra generated by a subset of the real line. "Let $\Delta= \{ ]a,b] : a,b \in R, a<b\}$. Define the $\sigma$-algebra generated by $\Delta$ "

Commented on How to your increase your mathematical maturity?. "I am math major who has spent a little over $2$ years at University and I think my mathematical maturity is a little over beginner level (I don't know whether I am under-rating or not) but it is not v"

Short question. Convergence of sequences in Rn. "Hy, I searched on the internet for a way to deduce that a sequence in Rn is convergent or divergent but I didn't find any useful information. "

Commented on ?=f{π(p+r)} - Formula Help!. "1.what does the ? formula mean, 2. What does the formula mean 3. what would happen if "?<+0" ? "

Commented on How to practically solve delayed differential equations. "I am interested on how to numerically solve a set of delayed differential equations. For example I have a set of differential equations: $y_1'(t) = y_1(t) + y_2(t-τ) + u_1(t)\\ y_2'(t) = y_2(t) + u_2"

Commented on Differentiation. Can you please help to solve this. "Can you please help me solve this question? X^3(2x+3). It's a differentiation questions. I have no idea what it is. "

Commented on Help me find the mistake in my solution of the limit. "Let $x_1=1, x_2=2,$ $$x_n=x_{n-1}+x_{n-2}, (n>2)$$ The task is to find: $$\lim \limits_{x\to\infty}\frac{x_{n+1}}{x_n}!$$ My attempt at solution: We write the recursive formula as: $$x_n-x_{n-1}-x_"

Commented on Squares, Square Roots, Cubes and Cube Roots. "Description: The area of the floor of a square room is 16m². 256 pieces of square tile of type P are needed to cover the floor. If square tiles of type Q are used, the number of tiles needed is reduce"

Commented on Putnam Question: Show that $a(n)=b(n+2)$. "Let $a(n)$ be the number of representations of positive integer $n$ as a sum of 1's and 2's taking order into account. $$ \text{Example $n=4$: } (1+1+1+1), (1+2+1),(1+1+2),(2+1+1),(2+2)\implies a(4)="

Short question. Equation solution in modular arithmetic. "Given two primes $11$ and $5$, find all $α > 1$ such that $α^{5} \equiv 1 \mod 11$. How would you compute that? "

Commented on Chenge weight function in shifted orthogonality. "We know that in Chebyshev orthogonal polynomial the weight function is $$1/\sqrt(1-x^2)$$ in interval $[-1,1]$. Do in shifted chebyshev orthogonal as example for interval $[0,1]$ the weight function c"

Commented on Converging/ Diverging Integrals. "Could someone please explain to me while the following question is diverging? And how you would go about to prove that it is. integral_1^3 x/(x^2-9)^(4/3)dx "

Short question. Basis of the space of bilinear maps. "Does anyone know an example of a basis for the space of bilinear maps $L^{2} (A, B; C)$ where A, B,C are normed spaces? "

Commented on Dice Conditional Probability Question. "I have the following problem to solve that deals with probability Three fair dice are thrown and we are told that at least one of the upturned faces shows a 2. Determine the probabilities of: Exac"

Short question. Limit $\lim _{x\to 0}\left(\frac{\arcsin \left(\sqrt{\sin \left(x\right)}\right)}{\sqrt{2x-x^2}}\right)$. "$$\lim _{x\to 0}\left(\frac{\arcsin \left(\sqrt{\sin \left(x\right)}\right)}{\sqrt{2x-x^2}}\right)=?$$ "

Short question. Why always in labeled tree the prüfer sequence is unique?. "If we decode the prüfer sequence into tree , we always get unique code for each tree? "

Commented on Find infimum of this equation. "I need to find infimum of this equation - {a/(b+c)+b/(a+c)+c/(a+b);a,b,c e R+} Some hint would be helpful "

Title contains ??. Short question. Is there are one more solution but Prony's method??. "Is there anyone who have ability to solve this problem? Here is problem: Can anyone can solve it? "

Commented on Question on one-sided derivatives. "Assume we have a function $f$, say on $\mathbb{R}$, such that $f$ is continuously differentiable in all $x$ smaller than some given $x_0 \in \mathbb{R}$. I am a bit confused about the connections of"

Title contains question. I cannot figure out what this question means with the semantic turnstile. "Hi I have recently started studying propositional logic and am finally understanding the truth tables and how to use them. I came across this formula which is confusing me. Use truth tables to estab"

Commented on Tough probability question: Random number generator. "A random number generator outputs integers from the set {1, 2, 3, 4, 5, 6, 7, 8}, with each of the eight choices equally likely. If ten such random integers are created, what is the probability that "

Short question. If the dot product between two vectors is 0, are they orthogonal?. "All of the theorems I have found in my textbook and on the internet just state the converse; is it true both ways? "

Short question. How many squares are in this image? Is there a method to check?. "In this image I have counted 14 but others say 18. Is there a method to check exactly? "

Commented on Can you help me answer this. "Can anyone please help me answer this someone asked me if you could that would be great enter image description here "

Commented on changing the independent variable of a functional. "Ok, so I'm working on obtaining Euler-Lagrange equations for functionals and have run into some confusion on changing the independent variable. Maybe I am missing something completely simple but woul"

Commented on how do I prove this polynomials question. "The given information is: f(1)=1/2 f(2)=f(1)+2/(2*2) f(3)=f(2)+3/(2*2*2) f(4)=f(3)+4/(2*2*2*2) ... f(n)=f(n-1)+n/(2^n) how do I prove f(n) < 2 ? "

Commented on Probababily Question. "There is $21$ balls in a bag numbered $1$ to $21$. Two balls are picked at random, without replacement. What is the probability of the lowest number on a ball being $17$ or greater? Is it simply $"

Commented on Show a unit disk with max metric is closed?. "I must show that if R2 is equipped with max metric, d = ((x1, x2),(y1, y2) = max{|x1 - y1| , |x2 - y2|} then the disk D = {(x1, x2) ∈ R2 : x12 + x22 ≤ 1 } is a closed set. My attempt (I'm jus"

Commented on Probability question.... " I think the given answer is incorrect as their might be a situation like GGBBBBBG where no boy is between two girls and it is not counted in favourable ways. According to me, required ways can be co"

Short question. Cofinality of two ordinals. "I would calculate cofinality of two ordinals: enter image description here I know that a cof(X) "

Short question. linear algebra ( infinite dimensional space). "Does someone have a reference (book) in linear algebra on infinite dimensional space ? I don't know anything in French Literature. "

Short question. Solve $\log_{2\sqrt{2+\sqrt{3}}}(x^2+2x-2)=\log_{{2+\sqrt{3}}}(x^2+2x-3)$. "How can I solve this equation? $$\log_{2\sqrt{2+\sqrt{3}}}(x^2+2x-2)=\log_{{2+\sqrt{3}}}(x^2+2x-3)$$ "

Tagged pde, differential-equations. Tagged differential-equations but mentions "partial". A general solution for a 2d pdf (ode). "I have the following 2 dimensional PDE: $$ \partial_{x_1}^2 u(x_1,x_2)+\frac{1}{x_1^2}\partial_{x_2}^2 u(x_1,x_2)+\frac{1}{x_1}u(x_1,x_2)=k $$ where $k>0$ is a constant, and $x_1\in[1,\infty)$, $0"

Commented on Find the limit in the given question. "What will be the limit [(log n)^n]/n as n tends to infinity? "

Tagged differential-equations but mentions "partial". Nonlinear ODE differential equation. "The following equation arises when minimizing certain non-equilibrium actions: $$\frac{\partial^2}{\partial t^2}y=(1+|y|^\alpha)f(t)$$ $f(t)$ is non-negative, smooth, and bounded. I am interested in c"

Title contains question. If $A$ and $B$ are open then so is $A \cap B$. (+another related question). "If $A \cap B = \emptyset$ then $A \cap B$ is vacuously open. If $A \cap B \neq \emptyset$ then since A,B are open, i.e $\forall z \in A \exists r>0 : D(z;r) \subset A $ similarly for B. we can find"

Short question. Combinatoric expression simplification. "we need help to simplification the expression in the picture. thank you. enter image description here "

Commented on Relationship/correlation between data - does it exist?. "Some analysis has been conducted for my business by an external company. The data, as it stands, only really tells part of the story and doesn't provide any real direction. The original study was co"

Commented on please , anwser that i need it ,. "we have a,b,c are nombrs complex a+b+c=1 and abc=1 and 1/a+1/b+1/c=1 find a and b and c "

Short question. Sequence y_n = y_n(x) (0 \leq x \leq 1 ). "$The function is defined as$ y_1 = \frac{x}{2} , y_n = \frac{x}{2} - \frac{y_{n-1}^2}{2} $Find \lim{y_n}: \lim_{n\to infty} "

Tagged pde, differential-equations. u_y + u*u_x = 1 Sketch a plot of Gamma and a few representative curves, including the envelope curve.. "... with u=0 on the curve y^2=2x, and y,x>0. Express u as a function of x,y. I'm new to PDE's and very lost. I saw similar problems on here, but not identical. I'm pretty sure I have to use the Metho"

Commented on An introduction to wavelet analysis by David F.. "If f_n(x)\to\f(x) in L^\infty\ on an interval I.then f_n(x)\to\f(x) pointwise on I. "

Commented on Simplify e^(ln(27)/3)?. "I don't want an exact answer to this. I just want to know how to SIMPLIFY it. What other format can you change e(ln(27)/3) into, and how? Note that it is NOT e ln(27/3), it is e(ln(27)/3). "

Short question. The given sequence y_n = y(x)_n ( 0 \leq x \ leq 1 ). "Sequence is defined : y_1 = \frac{x}{2} and y_n = \frac{x}{2} - \frac{y_{n-1}^2}{2} Find the limit as \mathbf{n} goes to infinity "

Commented on help calculating an integral. "I cant figure out how to calculate this integral, please help !! enter image description here alpha, beta, theta and r are real constants.. "

Short question. How to solve for the complex number $z$?. "How to solve for the complex number $z$? $$z^6=(z-1)^6$$ "

Short question. open dense subset of a Baire Space. "Let $X$ be a Baire Space and let $Y$ be a comeager subset of $X$. Is true that $Y$ contains an open dense subset of $X$? Thank you "

Short question. Inverse Laplace transforms. "I'm confusing about how can I find the inverse laplace transform for {( 20-3s^3+4s^5)\ s^8} Could you help me please! "

Commented on Book Recommendation for Measure Theory in n-Space. "What's a standard book on multidimensional measure theory? I'm aware of some books on functions of several variables, but they do not discuss measure theory or Lebesgue integration in space. Thanks."

Commented on $\forall \vec{u} \in V 0\vec{u} = \vec{0}$. "in class the teacher gave us a proof But I would like to see another $\forall \vec{u} \in V$(V is a vector space over a filed K) $0\vec{u} = \vec{0}$ My Proof: $0\vec{u} = 0\vec{u}$ $0\vec{u} + \v"

Short question. Demonstrate the existence of following limit using squeeze theorem. "$$\lim_{(x,y)\to(0,0)} \sqrt[3]x* e^\frac{-y^2}{x^2}$$ I have not idea what function to put in the inequality. Some aid? "

Commented on Number of solutions (x_1)(x_2)(x_3)(x_4) = 2016. "Having some trouble wrapping my head around this one: of solutions to the equation (x_1)(x_2)(x_3)(x_4) = 2016, where (x_i)s are integers that are not necessarily positive. Here's what I've been thi"

Commented on How do you find a basis for polynomial vector space?. "Let {1+t−t^3,1+t+t^2,1−t} and {t^3+t,2−t^3,2+t^3}be two basis of subspaces L and M. Find one basis of L+M and L∩M. "

Title contains question. Math Modeling Mortgage Question - $100000 mortgage paid over 30 yrs (360 months).. "Your parents are considering a 30-year, $100,000 mortgage that charges 0.5% interest each month. Formulate a model in terms of a monthly payment p that allows the mortgage (loan) to be paid off after "

Commented on Partial Fractions Integration Help?. "(click here for image of integral) So this is the integral and i have tried going through it many times and i can't seem to figure out where i went wrong. The answer in the box is the final answer i "

Commented on Can anyone help me get out of this Limit?. "I saw some resolutions here like $\sqrt{x+\sqrt{x+\sqrt{x}}}- \sqrt{x}$, but I couldn't get the point to solve this $\lim_{x\to\infty}\frac{\sqrt{x+\sqrt{x+\sqrt{x}}}}{x}$ I tried $\frac{1}{x}.(\sqr"

Short question. Does this sum have no meaning, no analytic solution or no-one knows. "Sum [Exp[i^2], {i,1,Infinity}] I am trying to understand what is known beyond an analytic boundary. "

Commented on Type of polynomial where leading coefficient is to the power of 6. "I need to identify the type of polynomial that a polynomial is based on the power of the leading coefficient. (Example x^2 = quadratic, x^3 = cubic, x^4 quartic). In this case, it is x^6. What is the "