use the contrapostive

it suffices to show if is not even, then is not even.

so assume is not even, so that for some integer n, then .....

same approach as aboveif a^2 is uneven, then prove that a is uneven too

by the way, "odd" means "uneven" and it sounds nicer.

Let be a rational number and be an irrational number. what can you say about their sum?And another problem:

prove that:

rational + irrational number = irrational number

PLS HELP ME!!!