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Let 
f(x)=-4x^(3)+6x^(2)-5.
The absolute minimum value of 
f over the closed interval 
-2 <= x <= 3 occurs at what 
x value?
Choose 1 answer:
(A) -2
(B) 1
(C) 3
(D) 0

Let f(x)=4x3+6x25 f(x)=-4 x^{3}+6 x^{2}-5 .\newlineThe absolute minimum value of f f over the closed interval 2x3 -2 \leq x \leq 3 occurs at what x x value?\newlineChoose 11 answer:\newline(A) 2-2\newline(B) 11\newline(C) 33\newline(D) 00

Full solution

Q. Let f(x)=4x3+6x25 f(x)=-4 x^{3}+6 x^{2}-5 .\newlineThe absolute minimum value of f f over the closed interval 2x3 -2 \leq x \leq 3 occurs at what x x value?\newlineChoose 11 answer:\newline(A) 2-2\newline(B) 11\newline(C) 33\newline(D) 00
  1. Find Derivative: To find the absolute minimum value of the function on the closed interval, we need to find the critical points of the function within the interval and evaluate the function at the endpoints of the interval.\newlineFirst, we find the derivative of the function f(x)=4x3+6x25f(x) = -4x^3 + 6x^2 - 5.\newlinef(x)=ddx(4x3+6x25)=12x2+12xf'(x) = \frac{d}{dx} (-4x^3 + 6x^2 - 5) = -12x^2 + 12x.
  2. Find Critical Points: Next, we find the critical points by setting the derivative equal to zero and solving for xx.
    12x2+12x=0-12x^2 + 12x = 0
    x(12x+12)=0x(-12x + 12) = 0
    x=0x = 0 or 12x+12=0-12x + 12 = 0
    x=0x = 0 or x=1x = 1
  3. Evaluate Function: We have two critical points within the interval: x=0x = 0 and x=1x = 1. Now we need to evaluate the function f(x)f(x) at these critical points and at the endpoints of the interval, x=2x = -2 and x=3x = 3.
    f(2)=4(2)3+6(2)25=4(8)+6(4)5=32+245=51f(-2) = -4(-2)^3 + 6(-2)^2 - 5 = -4(-8) + 6(4) - 5 = 32 + 24 - 5 = 51
    f(0)=4(0)3+6(0)25=5f(0) = -4(0)^3 + 6(0)^2 - 5 = -5
    f(1)=4(1)3+6(1)25=4+65=3f(1) = -4(1)^3 + 6(1)^2 - 5 = -4 + 6 - 5 = -3
    f(3)=4(3)3+6(3)25=4(27)+6(9)5=108+545=59f(3) = -4(3)^3 + 6(3)^2 - 5 = -4(27) + 6(9) - 5 = -108 + 54 - 5 = -59
  4. Compare Values: Now we compare the values of f(x)f(x) at x=2x = -2, x=0x = 0, x=1x = 1, and x=3x = 3 to find the smallest value, which will be the absolute minimum.\newlinef(2)=51f(-2) = 51\newlinef(0)=5f(0) = -5\newlinef(1)=3f(1) = -3\newlinef(3)=59f(3) = -59\newlineThe smallest value is f(3)=59f(3) = -59.
  5. Find Absolute Minimum: The absolute minimum value of f(x)f(x) over the closed interval [2,3][-2, 3] occurs at x=3x = 3.

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