Question

3^x-3^-x=10

Answer 1

Let y = 3^x

-> y - (1/y) = 10
y^2 - 1 = 10y
y^2 -10y -1 = 0
y = -.099 or 10.099

since 3^x > 0, y = 10.099
3^x = 10.099
take log of both sides
xlog(3) = log(10.099)

x = log(10.099)/log(3)

Answer 2

very nice solution :)