Question

x = 3 - root 8 than find the value of x cube + 1 by x cube

Answer 1

HEY MATE !!

YOUR QUESTION :

$x = 3 - \sqrt{8} then \: find \: value \: of \: {x}^{3} + \frac{1}{ {x}^{3} }$

ANSWER :-

$x = 3 - \sqrt{8} \\ \frac{1}{x} = \frac{1}{3 - \sqrt{8} } \\ \frac{1 \times </strong><strong>(</strong><strong>3</strong><strong> + \sqrt{8}</strong><strong>)</strong><strong> }{(3 - \sqrt{8}) (3 + \sqrt{8} )} \\ \frac{3 + \sqrt{8} }{3 - 8} \\ \frac{1}{ x} = \frac{3 + \sqrt{8} }{ - 5}$

so :

${x}^{3} + \frac{1}{ {x}^{3} } \\ {</strong><strong>(</strong><strong>3</strong><strong> - \sqrt{8} </strong><strong>)</strong><strong>}^{3} + {</strong><strong>(</strong><strong>\frac{1}{ \frac{3 + \sqrt{8} }{ - 5} }</strong><strong>)</strong><strong> }^{3} \\ {</strong><strong>(</strong><strong>3</strong><strong> - \sqrt{8} </strong><strong>)</strong><strong>}^{3} + {</strong><strong>(</strong><strong>\frac{ - 5}{3 + \sqrt{8} </strong><strong>}</strong><strong>)</strong><strong> }^{3}$

By using identity : a³ + b³ = (a + b)(a² + b² - ab)

you can easily solve this question.

Hope it Helps !!

Mark Brainliest !!

Answer 2

Answer:

hope this help you thanks