5.) which formula can be used to describe the sequence? -2/3, -4, -24, -144 a) f(x) = 6[-2/3]^x-1 b) f(x) = −6[2/3]^x-1 c) f(x) =-2/3(6)^x-1 d) f(x) = 2/3(−6)^x − 1

Let x = 1,2,3,4

Test f(x) = 6[-2/3]^(x-1).
f(x) = 6, -4, 8/3, -16/9        Incorrect

Test f(x) = -6[2/3]^(x-1)
f(x) = -6, -4, -8/3, -16/9     Incorrect

Test f(x) = (2/3)*6^(x-1)
f(x) = 2/3, 4, 24, 144         Incorrect

Test f(x) = (2/3)*(-6)^(x-1)
f(x) = -2/3, -4, -24, -144    Correct

The correct formula is f(x) = (2/3)*(-6)^(x-1)

Igot the answer of 15.8 years.