1. [15 points] Let k and l be integers. Prove that if l is even and k 2 + 2l is even, then k is even using a proof by contrapositive. Note: If you have two variables in your hypothesis and want to use the contrapositive law, the following rule applies: (p q) r (q r) p OR (p q) r (p r) q Essentially, you can keep one of p and q in your hypothesis and only "flip" the other one. You don't have to write it as (p q) r r (p q). Convince yourself that this is true