Plug in numbers. The first statement will work when a=3 and b=2, for example and then a2=9 and b2=4. However, it will not work when a=(−2) and b=(−3), then a2=4, and b2=9. The second statement is sufficient, it is possible to subtract d from both sides of the inequality and get: a+d−d>b+d−d, or a>b.