x=y
x^2=y^2
xy=y^2
xy-x^2=y^2-x^2
-x(x-y)=(x+y)(x-y)
-x=x+y
2x=y
2x=x
2=1
1=0
No me
Lets go through that with numbers
x = 2 y = 2
2 = 2
2^2 = 2^2
2 x 2 = 2^2
2 x 2 - 2^2 = 2^2 - 2^2
-2 x (2 - 2) = (2 + 2) x (2 - 2)
-2 = (2 + 2)
-2 = 4
Really, all you need is;
-2 x (2 - 2) = (2 + 2) x (2 - 2)
because you can cancel the (2 - 2) from each side,
-2 = (2 + 2)
Meaning -2 = 4, -3 = 6, -4 = 8
O_o Math class is meaningless.