Question

Which of the following exponential functions go through the points (1,12) and (2,36)?

A. f(x) = 4(3)^-x
B. f(x) = 3(4)^-x
C. f(x) = 3(4)^x
D. f(x) = 4(3)^x

Answer 1

D

Explanation:

Evaluate both points into each equation and see which works out..

A: f(1) = 4(3)^-1 = 4/3, it's supposed to be 12, so this equation is ruled out

B: f(1) = 3(4)^-1 = 3/4, ruled out for the same reason as A

C: f(1) = 3(4)^1 = 12, this works, now check the 2nd point...

f(2) = 3(4)² = 3(16) = 48, it's supposed to be 36, so this equation is ruled out

D: f(1) = 4(3)^1 = 12, this works, now check the 2nd point..

f(2) = 4(3)² = 4(9) = 36, this is what we wanted.