SAT Math Multiple Choice Question 41: Answer and Explanation

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Question: 41

1. Let the function f be defined such that f(x) = x2 - c, where c is a constant. If f(-2) = 6, what is the value of c ?

  • A. -10
  • B. -2
  • C. 0
  • D. 2

Correct Answer: B

Explanation:

B Start by plugging in what you know into the function given. If f(x) = x2 - c, and f(-2) = 6, then plug in -2 for x in the function: f(-2) = (-2)2 - c. Solve and replace f(-2) with 6: 6 = 4 - c; 2 = -c; and c = -2. If you picked (A), you forgot that (-2)2 is positive 4.

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