Can someone explain, showing steps, why this wouldn't have a solution?

Question

12/(x^2+9) + 3/(x+3) = 2/(x-3)

Thanks. :)

Answer 1

place all over the common denominator: (x-3)(x+3) and you have

12 + 3(x-3) = 2(x+3)
12 + 3x-9 = 2x+6
x = 3

But, 2/(x-3) is undefined in the original equation. The domain of f(x) excludes 3 and -3.