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Question
Expand (3p + 4q)3
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Solution
(3p + 4q)3
Comparing (3p + 4q)3 with (a + b)3 we have a = 3p and b = 4q
(a + b)3 = a3 + 3a2b + 3ab2 + b2
(3p + 4q)3 = (3p)3 + 3(3p)2(4q) + 3(3p)(4q)2 + (4q)3
= 33p3 + 3(9p2)(4q) + 9p(16q2) – 43q3
= 27p3 + 108p2q + 144pq3 + 64q3
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