1. The problem statement, all variables and given/known data dy/dx = (y^2 - 1)/ (x^2 - 1) with initial condition y(2) = 2 Why is y = 1 and/or y= -1 not solutions? 2. Relevant equations 3. The attempt at a solution I am actually able to solve this differential equation but when I separate the equation according to x and y: (y^2 - 1)^-1 dy = (x^2 - 1)^-1 dx here I am dividing both sides of the equation by (y^2 - 1), which means now I have to exclude y = 1 , -1 and check whether they are solutions Now how do I show that y =1 and y = -1 are not solutions?