$$\frac{x}{x^2+1}$$ I have to find the derivative and set a point by myself. So I just set $x=a$ ( is it correct?) and using the limit, $$ \lim_{h\to 0}\frac{f(a+h)-f(a)}{h} = \lim_{h \to 0} \frac{\frac{a+h}{(a+h)^2 + 1} - \frac{a}{a^2+1}}{h}$$ therefore, the answer is $$\frac{ 1-a^2}{(a^2+1)^...