Question

if n + 1/n= 7 then find the value of (n)3 + 1/(n)3

Answer 1

$(n + \frac{1}{n} )^{3} = n^{3} + \frac{1}{ {n}^{3} } + 3n \times \frac{1}{n} (n + \frac{1}{n} ) \\ = > 7 ^{3} = {n}^{3} + \frac{1}{ {n}^{3} } + 3(7) \\ = > {n}^{3} + \frac{1}{ {n}^{3} } = 343 - 21 = 322$

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