Question: prove 2 is equal to 1?
Answer: 1) a = b 1) Given. 2) a2 = ab 2) Multiply both sides by a. 3) a2-b2 = ab-b2 3) Subtract b2 from both sides. 4) (a+b)(a-b) = b(a-b) 4) Factor both sides. 5) (a+b) = b 5) Divide both sides by (a-b) 6) a+a = a 6) Substitute a for b. 7) 2a = a 7) Addition. 8) 2 = 1 8) Divide both sides by a.