If a3 – b3 = 2349 and (a – b) = 9, then (a + b)2 – ab is equal to what?
261
(a3 – b3 ) = (a – b) (a2 + ab + b2 )
⇒ 2349 = 9 (a2 + ab + b2)
⇒ (a2 + ab + b2) = (2349/9)
⇒ (a2 + ab + b2) = 261
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