Question 1137645: A student writes the five expression shown below
pq, qr, 7pr, r^2, p^2
The variables p,q, and r are rational numbers with the following properties: p>0
q<0
r<0
which pair have a negative value
Answer by greenestamps(13200)   (Show Source):
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Since p, q, and r are all non-zero, r^2 and p^2 are positive. Since you are looking for the expressions that have negative values, those can't be them.
The factor "7" is irrelevant in determining whether the expression is positive or negative; so essentially the three remaining answer choices are pq, qr, and pr.
The product of two non-zero numbers is negative if and only if one of the numbers is positive and the other is negative.
Which two pairs satisfy that condition?
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