SOLUTION: Hi what's the domain of log(e^(2x) - 3e^x -4). e^(2x) - 3e^x -4>0 --> e^x = t t^2-3t-4>0 t=(3+19^(1/2))/-8 --> (3+19^(1/2))/-8 = e^x How can I continue? thanks

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: Hi what's the domain of log(e^(2x) - 3e^x -4). e^(2x) - 3e^x -4>0 --> e^x = t t^2-3t-4>0 t=(3+19^(1/2))/-8 --> (3+19^(1/2))/-8 = e^x How can I continue? thanks      Log On


   

Question 865865: Hi what's the domain of log(e^(2x) - 3e^x -4).
e^(2x) - 3e^x -4>0 --> e^x = t
t^2-3t-4>0
t=(3+19^(1/2))/-8 --> (3+19^(1/2))/-8 = e^x
How can I continue? thanks
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Not sure how you got from line 3 to line 4.
t%5E2-3t-4%3E0
%28t-4%29%28t%2B1%29%3E0
.
.
.
graph%28300%2C300%2C-5%2C5%2C-5%2C5%2C%28x-4%29%28x%2B1%29%29
.
.
.
t-4%3E0 and t%2B1%3C0
t%3E4 and t%3C-1
e%5Ex%3E4 and e%5Ex%3C-1
The second solution is not possible so we discard it.
e%5Ex%3E4
x%3Eln%284%29