Question

Is `f(x)=(x+4)^2+x^2-3x` increasing or decreasing at `x=-2`?

Answer 1

Decreasing.

Explanation:

After simplifying,

`f(x) = 2x^2 +5x +16`

Differentiate w.r.t. `x`.

`f'(x) = 4x + 5`

`f'(-2) = -3 < 0`

Gradient is negative.

Decreasing.