Question
The coefficient of ‘b2’ in (3a +
b)3 isSolution
= (3a + b)3 = (3a)3 + b3 + 3 × (3a)2 × b + 3 × 3a × b2 = 27a3 + b3 + 27ba2 + 9ab2 So, coefficient of ‘b2’ = 9a
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