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Question
If m - n = -2 and m3 - n3 = -26, find mn.
Sum
Solution
m - n = -2, m3 - n3 = -26
(m - n)3 = m3 - n3 - 3mn (m - n)
⇒ (-2)3 = -26 - 3mn (-2)
⇒ 6mn
= - 8 + 26
= 18
⇒ mn = 3.
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