Question 914785
Provided: e^(4x) + 4e^(2x) − 12 = 0
Use the substitution t = e^(2x)
solve for x 
t^2=e^4x
t^2+4t-12=0
(t+6)(t-2)=0
t=2=e^(2x)
2xlne=ln2
2x=ln2
x=ln2/2≈0.36