SOLUTION: Please help!! solve the following exponential equation. 2^2+2t + 3(2^t) - 1 = 0

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: Please help!! solve the following exponential equation. 2^2+2t + 3(2^t) - 1 = 0      Log On


   

Question 869378: Please help!!
solve the following exponential equation.
2^2+2t + 3(2^t) - 1 = 0
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
I corrected what I think is a missing parentheses in the first term.
2%5E%282%2B2t%29+%2B+3%282%5Et%29+-+1+=+0
4%2A2%5E%282t%29%2B3%2A2%5Et-1=0
Substitute,
u=2%5Et
u%5E2=2%5E%282t%29
4u%5E2%2B3u-1=0
%28u%2B1%29%284u-1%29=0
Only the positive solution makes sense for this problem.
4u-1=0
4u=1
u=1%2F4
2%5Et=1%2F4
t=-2