please help me!!!!

Question

the first 5 terms of the sequence are shown

4, 12, 36, 108, 324

which function models the value of the nth term in the sequence such that f(1)=4

a. f(x)=3(4)^x

b. f(x)=3(4)^x-1

c. f(x)=4(3)^x-1

d. f(x)=12(3)^x-1

Answer 1

Right answer is f(x) = 4·3^{x - 1}_;

_{whic is c.}

Answer 2

d), it is a geometric sequence with ratio = 3.