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प्रश्न
if `x^2 + 1/x^2 = 79` Find the value of `x + 1/x`
उत्तर
We have
`(x + 1/x)^2 = x^2 + 1/x^2 + 2 xx x xx 1/x`
`=> (x + 1/x)^2 = (x^2 + 1/x^2) + 2`
`=> (x + 1/x)^2 = 79 + 2`
`=> (x + 1/x)^2 = 81`
`=> (x + 1/x)^2 = (+-9)^2`
`=> x + 1/x = +-9`
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