Answer: x = 3
Step-by-step explanation:
Subtract 1
2^x = 8
Take the log.
x·log(2) = log(8)
Divide by the coefficient of x.
x = log(8)/log(2) = log₂(8)
We know that 8 = 2³, so log₂(8) = 3.
x = 3
_____
If your equation is ...
2^(x+1) = 9
then
x + 1 = log(9)/log(2)
x = log(9)/log(2) -1 . . . . . . change of base formula can be used, but isn't helpful unless you have a calculator that computes log₂(9).
x ≈ 2.170
