InterviewSolution
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InterviewSolution
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Expand (i) (3a – 4b)3 (ii) (x + \(\frac{1}{y}\))3 |
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Answer» (i) (3a – 4b)3 We know that (x – y)3 = x3 – 3x2y + 3xy2 – y3 (3a - 4b)3 = (3a)3 – 3(3a)2 (4b) + 3(3a)(4b)2 – (4b)3 = 27a3 – 108a2b + 144 ab2 – 64b3 (ii) (x + \(\frac{1}{y}\))3 (x + y)3 ≡ x3 + 3x2y + 3xy2 + y3 (x + \(\frac{1}{y}\))3 = x3 + \(\frac{3x^2}{y}+\frac{3x}{y^2}+\frac{1}{y^3}\) |
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