He Really is a Genius

So he showed me how to prove that 2=1 so i thought I'd share it with yall.
a=b
multiply both sides by a and you get:    (a^2)=ab
subtract b squared from both sides and you get:    (a^2)-(b^2)=ab-(b^2)
factor that and you get:    (a-b)(a+b)=b(a-b)
then divide both sides by (a-b) and you get:    a+b=b
since a= b substitute it back in and you get:    b+b=b
and therefore:    2b=b
divide both sides by b and you get:    2=1
taddaaah he is a genius...if you figure out why or why not this works post,
unless you have seen it before,answer with a comment.