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प्रश्न
If a + b = 5 and ab = 2, find a3 + b3.
बेरीज
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उत्तर
Using (a + b)2 = a2 + 2ab + b2
a2 + b2 = (a + b)2 - 2ab
⇒ a2 + b2 = (5)2 - 2(2)
⇒ a2 + b2 = 25 - 4
⇒ a2 + b2 = 21
a3 + b3
= (a + b) (a2 + b2 - ab)
= (5) (21 - 2)
= (5) (19)
= 95.
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