Topic: faulty proof

One item is filed under this topic.

Question:

(x^{2}-x^{2}) = (x^{2}-x^{2}) x(x-x) = (x+x)(x-x) [divide both sides by (x-x)] x = x + x x = 2x [divide both sides by x] 2 = x/x = 1

Where is the flaw in this problem?