How do you differentiate #f(x)=(x^3-x)(x+3) # using the product rule?
1 Answer
Jan 2, 2016
Explanation:
The product rule:
#d/dx[f(x)g(x)]=f'(x)g(x)+g'(x)f(x)#
Thus,
#f'(x)=(x+3)d/dx(x^3-x)+(x^3-x)d/dx(x+3)#
Find each derivative.
#d/dx(x^3-x)=3x^2-1#
#d/dx(x+3)=1#
Plug these both back in.
#f'(x)=(x+3)(3x^2-1)+(x^3+x)(1)#
Simplify.
#f'(x)=4x^3+9x^2-3#