If y= e(power x)+ e(power -x)/2,find x when y = 1

y = (e^x + e^-x)/2

1 = (e^x + e^-x)/2
e^x + e^-x = 2
let e^x = t
t^2 + t - 2 = 0
(t+2)(t-1) = 0
t = -2 or t = 1
e^-x = 1
e^x = 1
x = 0
or
e^-x = -2
e^x = -1/2 , ---> no real solution

so x = 0