1.

For what values of x is the rate of increase of `x^(3)-5x^(2)+5x+8` is twice the rate of increase of x?A. `-3, -(1)/(3)`B. `-3, (1)/(3)`C. `3, -(1)/(3)`D. `3, (1)/(3)`

Answer» Correct Answer - D
Let `y=x^(3)-5x^(2)+5x+8`. Then,
`(dy)/(dt)=(3x^(2)-10x+5)(dx)/(dt)`
When `(dy)/(dt)=2(dx)/(dt)`, we have
`(3x^(2)-10x+5)(dx)/(dt)=2(dx)/(dt)`
`implies 3x^(2)-10x+3=0`
`implies(3x-1)(x-3)=0`
`impliesx=3,(1)/(3)`


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