Problem #PRU-5090

Problems Mathematical logic

Problem

Let’s prove that 1=2. Take a number a and suppose b=a. After multiplying both sides we have a2=ab. Subtract b2 from both sides to get a2b2=abb2. The left hand side is a difference of two squares so (ab)(a+b)=b(ab). We can cancel out ab and obtain that a+b=b. But remember from the start that a=b, so substituting a for b we see that 2b=b, dividing by b we see that 2=1.