Question let-th

2.1 Nonlinear Functions - Function composition and evaluation
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Let the function p be defined as p of x equals, the fraction with numerator, open parenthesis, x minus c, close parenthesis, squared, plus, 160, and denominator, 2 c , end fraction, where c is a constant. If p of c equals, 10, what is the value of p of 12 ?

A.

10.00

B.

10.25

C.

10.75

D.

11.00

Let the function p be defined as , where c is a constant. If , what

Hard-difficulty · SAT Math · Nonlinear Functions — Function composition and evaluation. Read the question above, select your answer, and check the full explanation below to understand exactly why the correct choice works.

Answer explanation

Choice D is correct. The value of p(12) depends on the value of the constant c, so the value of c must first be determined. It is given that p(c) = 10. Based on the definition of p, it follows that:

p of c equals, the fraction with numerator open parenthesis, c minus c, close parenthesis, squared, plus 160, and denominator 2 c, end fraction, which equals 10

the fraction 160 over 2 c, end fraction, equals 10

2 c equals 16

c equals 8

This means that p of x equals, the fraction with numerator open parenthesis, x minus 8, close parenthesis, squared, plus 160, and denominator 16 for all values of x. Therefore:

p of 12 equals, the fraction with numerator open parenthesis, 12 minus 8, close parenthesis, squared, plus 160, and denominator 16

which equals the fraction with numerator 16 plus 160, and denominator 16

which equals 11

Choice A is incorrect. It is the value of p(8), not p(12). Choices B and C are incorrect. If one of these values were correct, then x = 12 and the selected value of p(12) could be substituted into the equation to solve for c. However, the values of c that result from choices B and C each result in p(c) < 10.