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  1. If a + b = 3, then the value of a3 + b3 + 9ab – 27 is
    1. 24
    2. 25
    3. 0
    4. 27
Correct Option: C

a + b = 3
On cubing both sides,
(a + b)3 = 33
⇒  a3 + b3 + 3ab (a + b) = 27
⇒  a3 + b3 + 3ab × 3 = 27
⇒  a3 + b3 + 9ab – 27 = 0


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