Question

I need help deriving : (7x)/(3+x^2), I keep on deriving it wrong and I am not sure as to why

Answer 1

$\bf y=\cfrac{7x}{3+x^2}\implies \cfrac{dy}{dx}=\stackrel{quotient~rule}{\cfrac{7(3+x^2)-7x(0+2x)}{(3+x^2)^2}} \\\\\\ \cfrac{dy}{dx}=\cfrac{21+7x^2-14x^2}{(3+x^2)^2}\implies \cfrac{dy}{dx}=\cfrac{21-7x^2}{(3+x^2)^2}\implies \cfrac{dy}{dx}=\cfrac{7(3-x^2)}{(3+x^2)^2}$