Question

e^(4x)+5e^(2x)-14=0

Answer 1

rewrite that first term as:

(e^(2x))^2
so now you'll have the exponential equation in quadratic form...

Answer 2

If e ^ (2x) = 2,
then ln ((e ^ (2x) ) = ln (2)
2x (ln(e)) = ln (2)
2x = ln (2)
x =[ ln (2)] / 2