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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) |
