# Pre-Calc

posted by
**Sarah** on
.

I'm stuck on a pre-calc problem. I need to find y as a function of x, where the constant c is a positive number for In(y-1)+In(y+1)= -x+c

express your question as

ln[(y-1)(y+1)] = -x+c

change that to exponential form

e^(-x+c) = (y-1)(y+1)

e^(-x+c) = y^2 - 1

y^2 = e^(-x+c) + 1

y = ± sqrt(e^(-x+c) + 1)