solve the following exponential equation

Question

e^x-4=-e^-x

please show work

Answer 1

if you let u = e^x,

u-4 = -1/u
u^2 - 4u = -1
u^2 - 4u + 1 = 0
now just use the quadratic formula and if you get values for u, wind up with

x = ln(u) if defined