Is f(x)=-3x^3-5x^2-x-1 increasing or decreasing at x=-2?
1 Answer
Feb 9, 2016
Decreasing.
Explanation:
Find the sign of the first derivative at
- If
f'(-2)<0 , thenf(x) is decreasing atx=-2 . - If
f'(-2)>0 , thenf(x) is increasing atx=-2 .
To find the derivative of the function, use the power rule.
f(x)=-3x^3-5x^2-x-1
f'(x)=-9x^2-10x-1
The sign of the derivative at
f'(-2)=-9(-2)^2-10(-2)-1=-36+20-1=ul(-17
Since this is
graph{-3x^3-5x^2-x-1 [-4, 2, -12, 15]}