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Practicing Success
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The interval where the function $f(x)=2x^3-9x^2+12x+15$ is decreasing, is : |
[1, 2] (-∞, 1] ∪ [2, ∞) (-∞, 2) (2, ∞) |
[1, 2] |
The correct answer is Option (1) → [1, 2] $y=2x^3-9x^2+12x+15$ $\frac{dy}{dx}=6x^2-18x+12=0⇒x^2-3x+2=0$ $⇒(x-2)(x-1)=0$ so $x=1,2$ using wavy curve method
f(x) is decreasing in [1, 2] |
