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If a -b 7 and a2 + b 85 then find a3 - b3. |
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Answer» a-b=7a²+b²=85 (a-b)²=a²+b²+2ab7²=85+2ab.2ab=49-85=-36 ab=-18 (a-b)³=a³-b³+3ab(a-b)7³=a³-b³+3(-18)(7)343+378=a³-b³=721 |
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