SAT Math Multiple Choice Practice Question 514: Answer and Explanation
13. If f(2) = 10 and f(4) = 44, which of the following could be f(x) ?
A. 2x + 6
B. 2x2 + 12
C. 2x3 + 2
D. 2x3 – 4x
E. 3x2 – x
Correct Answer: E
E Let's plug x = 2 and x = 4 into the answer choices, and see which choice makes f(2) = 10 and f(4) = 44. If you plug 2 into A, you get 10. B gives you 20. C gives you 18, and D gives you 8. E gives you 10; leave it in. Now plug in x = 4 into the choices that remain. A gives you 14, so eliminate it. E gives you 44. Only E works for both of our numbers, so it must be the answer.