Question

e^2x - 2e^x = +8 then x = ???

Answer 1

Think of this as a quadratic

Answer 2

Just move the eight to the other side,
(e^x)^2 -2e^x - 8 = 0

Answer 3

or how about let z = e^x
(z)^2 -2z - 8 = 0

Answer 4

or factor direct can be (e^x - 4)(e^x + 2) = 0

Answer 5

now, for zeros all terms
take e^x-4=0 or e^x+2=0,
solve for x's!