So yeah, basically I got my GCSE Maths result back, and I only dropped one mark, but I'm not sure how or where I lost it. I'll post my method, and then you guys can tell me what I did wrong.
Question: Prove that the sum of two consecutive odd integers is always even.
My method;
Let two consecutive odd integers be
and
.
Hence,
Since twice anything is always even;
, which is true. Therefore, the sum of two consecutive odd integers is always even. Any idea where I dropped the mark? I only got two of a possible three.