Given that y = cosh^-1 (x) , Show that y = ln(x+ sqrt(x^2-1))

Have a picture of full working with annotation to go through during interview.Here is rough outline:y = cosh^-1(x)x = cosh(y)x = (e^y+e^-y)/22x = e^y+e^-ye^y+e^-y -2x = 0Turn into hidden quadratic by multiplying by e^ye^2y-2xe^y+1=0By quadratic formula:e^y = x +/- sqrt(x²-1)Take positive root in order to make inverse function 1 to 1.y = ln(x + sqrt(x²-1)