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A: Calculus (value of $c$)

Varun IyerYes you can use implicit differentiation. Therefore, taking the derivative $$8x + c -2e^yy' = 0$$ When $x =0$, $y' =4$ Also, finding the value of $y$ $$0 + 0 -2e^y = -2$$ So, $y = 0$ Substituting this into our equation for the derivative: $$0 + c - 2*e^0*4= 0$$ $$0 + c - 2*1*4= 0$$ $$c = ...

 
Hello
Hello
I don't get why you added $y'$ right next to $-2e^y$. I know you took the derivative.
 
Varun Iyer
Varun Iyer
Because we are differentiating with respect with x, in order to take the derivative of the variable $y$ in terms of $x$, we must represent it as $\frac{dy}{dx}$, or in short hand, $y'$. take a look at this: sosmath.com/calculus/diff/der05/der05.html
 
Hello
Hello
I understand. I was taught with $dy/dx$ so i got confused.
 
Varun Iyer
Varun Iyer
@Hello sorry for the confusion. It easier for me to write it in short hand notation :).
 
Hello
Hello
Where did the $y$ go?
 
Varun Iyer
Varun Iyer
1:40 AM
@Hello in which part?
 
Hello
Hello
in the last part. wait you just edited it, let me look
 
Varun Iyer
Varun Iyer
I substituted the value of y that I found, $0$, into the equation that is the derivative.
Hi again
so
 
Hello
Hello
Where did $c$ go in $0+0-2e^y=-2$?
 
Varun Iyer
Varun Iyer
It was $cx$
since $x$ was 0
 
Hello
Hello
truwe
 
Varun Iyer
Varun Iyer
1:42 AM
the term $cx$ was 0
 
Hello
Hello
true*
i understand it. thanks
 
Varun Iyer
Varun Iyer
okay
if you need anymore help
just ask
 
Hello
Hello
why did you plug in 0 to the original?
@VarunIyer
 
 
5 hours later…
Hello
Hello
6:33 AM
errr
 
 
4 hours later…
Hello
Hello
10:56 AM
@skullpatrol you there?
 
skullpatrol
skullpatrol
@Hello yes
 
Hello
Hello
@skullpatrol can i ask you a math question?
 
skullpatrol
skullpatrol
I can't stay for long...
 
Hello
Hello
quickly
 
skullpatrol
skullpatrol
I will try
 
Hello
Hello
10:57 AM
if i do a 1st der test and it goes - + - + does that mean the interval of inc/dec will go [x,y] U [x,y] U [x,y] U [x,y] ?
well not x and y. i have the required values
basically what im asking is can there be 4 like that?
 
skullpatrol
skullpatrol
yes there can
 
Hello
Hello
ok so when i set the der=0 and get 3 values, i then do the test and get 4 brackets?
 
skullpatrol
skullpatrol
yes that is a good plan, but like i said in the math room, the best thing to do is to go to the library and find a calculus book and follow the set method given there.
 
Hello
Hello
well i did learn this stuff in precalc, i just needed a refresher
 
skullpatrol
skullpatrol
but do you have the textbook?
 
Hello
Hello
11:03 AM
no i gave it back since the school year ended
and for inc/dec it's hard brackets correct?
 
skullpatrol
skullpatrol
It depends on the nature of the function you are working with.

What I am saying, is buy a good book and refer to it constantly.
But first go to a university library and find one :-)
Or a university book store.
 
Hello
Hello
well school starts next week, and my teacher isn't grading the assignment since it's an ap exam and i just finished precalc. so i'll be refreshed soon
 
skullpatrol
skullpatrol
Ok, I gotta run, good luck
 
Hello
Hello
bye
 

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