9514 1404 393
Answer:
a) {-6, 2}
b) -12
c) minimum: -16
Step-by-step explanation:
I find a graphing calculator to be a big help. Its graph is attached.
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a) The function can be factored as ...
f(x) = (x -2)(x +6)
The factors are zero at the x-intercepts: x = 2, x = -6.
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b) The y-intercept is the function value when x=0. That is the constant in the function. The y-intercept is -12.
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c) The leading coefficient of the function is positive, so its graph opens upward. The extreme value is a minimum. It is found on the axis of symmetry, at the x-value that is halfway between the x-intercepts: x = (2-6)/2 = -2. The function value there is ...
f(-2) = (-2-2)(-2+6) = -4(4) = -16
The minimum is f(-2) = -16.