Question 450586
a: |p| is positive is not always true. Note that p could equal 0, and |0| = 0, which is not positive.


b: -q is negative is also not always true, since q could be negative. For example, if q = -1, then -q = -(-1) = 1.


c: This must always be true. If p = -q, then p + q = (-q) + q = 0 (for all values p,q with p = -q)