If x=(4-√15), find the value of [x+1/x].

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Solution

x = 4 + √ 15

1 / x = 1/ ( 4 + √ 15) * (4 - √ 15) / ( 4 - √ 15) = 4 - √ 15

x + 1 / x = 4 + √ 15 + 4 - √ 15 = 8

x2 + 1 / x2 = ( x + 1 / x)2 - 2

x2 + 1 / x2 = 82 - 2 = 64 - 2 = 62

Ans: 62

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x = (4 - \sqrt{15})

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If $x + \sqrt{15} = 4,$ then find the value of $x + \frac{1}{x}$ .

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