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

D

Step-by-step 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.  

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so:

30

step-by-step explanation:

times by times