Find the sum of all x that satisfy the equation -9x/(x^2 - 1) = 2x/(x + 1) - 8(x - 1).
x^2 - 1 = (x +1) (x -1)
Multiply through by the factorization and we have that
-9x = 2x ( x - 1) - 8 ( x + 1)
-9x = 2x^2 -2x - 8x - 8
2x^2 - x - 8 = 0
The sum of the solutions in the form ax^2 + bx + c = 0 = -b/ a = = 1 / 2
