The interval on which the function $f(x)=2x^3+12x^2+18x-7$ is decreasing, is :

[-3, -1] (-2, -1) [-3, 0] [-2, -1]

[-3, -1]

The correct answer is Option (1) → [-3, -1] $f(x)=2x^3+12x^2+18x-7$ $f'(x)=6x^2+24x+18=0$ $x^2+4x+3=0$ $(x+3)(x+1)=0$ $⇒x=-3,-1$ Using wavy curve method ⇒ f is decreasing in [-3, -1]