Question

Is `f(x)=-2x^2-2x-1` increasing or decreasing at `x=-1`?

Answer 1

It is increasing at `x=-1`.

Explanation:

`color(white)(xx)f(x)=-2x^2-2x-1`

`=>f'(x)=-4x-2`
`=>f'(-1)=4-2`
`color(white)(xxxxxxxx)=2`

`=>f'(-1)>0`

Therefore `f(x)` is increasing at `x=-1`.
graph{-2x^2-2x-1 [-10, 10, -5, 5]}