If 3^x-2=81 what is the value of 2^2x - 7

Answer 1

if 3^(x-2) = 81 what is 2^(2x-7)

x = 1/9 = .111....

then 2^(2/9 -7) = 2^(-61/9) = about .00911

UNLESS you really meant 3^x -2= 81 then 3^x = 83

and x = ever so slightly over 4

then 2^2x -7 = about 2^8 -7 = about 356-7 = 349

Answer 2

Hi Mel, I would advice you to always consider the use of parenthesis on exponential equations or algebraic expressions. A solution to this problem would be:

1. 3^(x-2) = 81

3^(x-2) = 3^(4)

x-2 = 4

x = 6

1. 2^((2*x)-7) = 2^((2*6)-7) = 2^(12-7) = 2^(5) = 32