Question

if x minus 1 by x = 3 . find x cube minus 1 by x cube ​

Answer 1

x - (1/x) = 3

We are aware of the identity

a³ - b³ = (a - b)³ + 3ab(a - b)

So

x³ - (1/x)³

= (x - 1/x)³ + 3*x*(1/x)*(x - 1/x)

= 3³ + 3×1×3

= 27 + 9

= 36

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Answer 2

Answer:

$\frac{x - 1}{x} = 3$

x-1 = 3x

-1 = 3x - x

-1= 2x

x = -1/2

$\frac{ {x}^{3} - 1 }{ {x}^{3} } = \frac{ { \frac{ - 1}{2} }^{3} - 1 }{ \frac{ { - 1}^{3} }{2} } = \frac{ \frac{ - 1}{8} - 1}{ \frac{ - 1}{8} } = \frac{ \frac{ - 1 - 8}{8} }{ \frac{ - 1}{8} } = 9$