Question

x+1/x=7,Find x^3+1/x^3

Answer 1

Hey friend,
Here is the answer you were looking for:
$x + \frac{1}{x} = 7 \\ \\ then \\ {( x + \frac{1}{x} )}^{3} = {(7)}^{3} \\ \\ by \: using \: the \: formula \\ {(a + b)}^{3} = {a}^{3} + {b}^{3} + 3ab(a + b) \\ \\ {x}^{3} + \frac{1}{ {x}^{3} } + 3 \times x \times \frac{1}{x} (x + \frac{1}{x} ) = 343 \\ \\ {x}^{3} + \frac{1}{ {x}^{3} } + 3(7) = 343 \\ \\ {x}^{3} + \frac{1}{ {x}^{3} } = 343 - 21 \\ \\ {x}^{3} + \frac{1}{ {x}^{3} } = 322$

Hope this helps!!!

@Mahak24

Thanks...
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