Does 17 divide each of these numbers (just answer yes orno)?

1. 68 b) 84

3. 357 d) 1001

Show that if a | b and b | a, where a and bare integers, then a = b or a = -b.

Show that if a, b, c, and d are integers,where a 0, suchthat a | c and b | d, then ab |cd.

Prove that if a and b are nonzero integers, a | b, anda + b is odd, then a is odd.

Prove that if a is an integer that is not divisible by3, then (a+1)(a+2) is divisible by3.