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The interval in which $f(x)=2x^3-9x^2+12x+1$ is decreasing is : |
R [1, 2] [2, 3] [3, 4] |
[1, 2] |
The correct answer is Option (2) → [1, 2] $f(x)=2x^3-9x^2+12x+1$ $f'(x)=6x^2-18x+12=0$ $⇒x^2-3x+2=0$ so $x^2-2x-x+2=0$ $(x-2)(x-1)=0⇒x=1,2$
f(x) decreasing in [1, 2] |
