If f(x)= - x^2 + x and g(x) = sqrtx + x , how do you differentiate f(g(x)) using the chain rule?

1 Answer
May 17, 2018

-1-2sqrt(x)-x/sqrt(x)-2x

Explanation:

Assuming you already know the chain rule. If not:
Given h(x) is a composite function consisting of 2 functions such that h(x)=f(g(x)), h'(x)=f'(g(x))g'(x).

So, in this scenario, f'(x)=-2x and g'(x)=1/(2(sqrt(x)))+1
Substitute g(x) into f'(x):
-2(sqrt(x)+x)
And multiply by g'(x):
-2(sqrt(x)+x)*(1/(2sqrt(x))+1)
-2(1/2+sqrt(x)+x/(2sqrt(x))+x)
-1-2sqrt(x)-x/sqrt(x)-2x