If p + q = 12 and p² − q² = 72, then what is the value of p - q?
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Correct answer: D
Explanation
p + q = 12
p² − q² = 72
According to the formula:
p² − q² = (p + q)(p − q)
(p + q)(p − q) = 72
12(p − q) = 72
p − q = 72 / 12
p − q = 6