The function $f(x)= -2x^3-9x^2-12x+5$ is :

increasing in (-2, -1) and decreasing in (-∞,-2) ∪ (-1, ∞)

The correct answer is Option (1) → increasing in (-2, -1) and decreasing in (-∞,-2) ∪ (-1, ∞)

$f(x)=-2x^3-9x^2-12x+5$

$f'(x)=-6x^2-18x-12=0$

$⇒-x^2-3x-2=0$

so $-(x+2)(x+1)=0$

$x=-1,-2$

Using wavy curve

$f(x)$ increasing in (-2, -1) and decreasing in (-∞,-2) ∪ (-1, ∞)