f(x) = x^2 - x. For which of the following values of "a" is f(a) ≥ f(8)?
I. a = -7
II. a = -8
III. a = -9
A. I only
B. II only
C. III only
D. I and II only
E. I, II, and III
[spoiler]OA=E[/spoiler]
Source: Veritas Prep
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f(x) = x^2 - x. For which of the following values of a is
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GIVEN: f(x) = x² - xVJesus12 wrote:f(x) = x² - x. For which of the following values of "a" is f(a) ≥ f(8)?
I. a = -7
II. a = -8
III. a = -9
A. I only
B. II only
C. III only
D. I and II only
E. I, II, and III
So, f(8) = 8² - 8 = 56
I. a = -7
So, f(-7) = (-7)² - (-7) = 56
This means f(a) ≥ f(8)
Check the answer choices. . . ELIMINATE B and C
II. a = -8
So, f(-8) = (-8)² - (-8) = 72
This means f(a) ≥ f(8)
Check the answer choices. . . ELIMINATE A
II. a = -9
So, f(-9) = (-9)² - (-9) = 90
This means f(a) ≥ f(8)
Check the answer choices. . . ELIMINATE D
Answer: E
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f(8) = 8^2 - 8 = 64 - 8 = 56VJesus12 wrote:f(x) = x^2 - x. For which of the following values of "a" is f(a) ≥ f(8)?
I. a = -7
II. a = -8
III. a = -9
A. I only
B. II only
C. III only
D. I and II only
E. I, II, and III
[spoiler]OA=E[/spoiler]
Source: Veritas Prep
Let's analyze each Roman numeral:
I. a = -7
f(-7) = (-7)^2 - (-7) = 49 + 7 = 56. Yes, f(-7) ≥ f(8) because 56 ≥ 56.
II. a = - 8
f(-8) = (-8)^2 - (-8) = 64 + 8 = 72. Yes, f(-8) ≥ f(8) because 72 ≥ 56.
III. a = -9
f(-9) = (-9)^2 - (-9) = 81 + 9 = 90. Yes, f(-9) ≥ f(8) because 90 ≥ 56.
Answer: E
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