If a4 - b4 = 609, a - b = 7 and a3 + b3 = 117, then what is the value of a2b + ab2?
If a4 - b4 = 609, a - b = 7 and a3 + b3 = 117, then what is the value of a2b + ab2? Correct Answer -30
a4 - b4 = (a2 + b2)(a2 - b2)
a4 - b4 = (a2 + b2)(a + b)(a - b)
a4 - b4 = (a3 + ab2 + a2b + b3)(a - b)
Now,
609 = (117 + a2b + ab2) × 7
(117 + a2b + ab2) = 87
(a2b + ab2) = -30
মোঃ আরিফুল ইসলাম
Feb 20, 2025