Question

if x-1/x=7 then find the value of xcube-1/xcube with the help of formula

Answer 1

Answer:

$if \: \frac{x - 1}{x} = 7$

$\frac{x - 1}{x} = 7$

$x - 1 = 7 \times x$

$x - 1 = 7x$

$- 1 = 7x - x$

$- 1 = 6x$

$\frac{ - 1}{6} = x$

$so \: value \: of \: x \: is \: \frac{ - 1}{6} .$

$\: value \: of \: \frac{x {}^{3} - 1 }{x {}^{3} }$

$putting \: value \: of \: x = \frac{ - 1}{6}$

$\frac{ \frac{( - 1) {}^{3} }{(6) {}^{3} } - 1}{ \frac{( - 1) {}^{3} }{(6) {}^{3} } }$

$\frac{ \frac{ - 1}{216} - 1}{ \frac{ - 1}{216} }$

$\frac{ \frac{ - 1 - 216}{216} }{ \frac{ - 1}{216} }$

$\frac{ \frac{ - 217}{216} }{ \frac{ - 1}{216} }$

$\frac{ - 217 \times 216}{216 \times - 1}$

$\frac{ - 46872}{ - 216}$

$= \frac{46872}{216}$

$= 217$

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