Proof that 2=1

Let
Let a = b

Multiply both sides by a
a2 = ab

Add a2 to both sides
a2 + a2 = a2 + ab

Collect like terms on both sides
2a2= a2 + ab

Subtract 2ab from both sides
2a2 - 2ab= a2 + ab - 2ab

Factor the left side, and collect like terms on the right side.
2(a2 - ab) = a2 - ab

Divide both sides by (a2 - ab)
2= 1