Math, asked by agrawaltanmaya, 2 months ago

if x-1/x =7 then find x³-1/x³​

Answers

Answered by kamalrajatjoshi94
1

Answer:

Given:-

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

Identity used:-

 {(a - b)}^{3}  =  {a}^{3}  -  {b}^{3} - 3ab(a - b)

Solution:-

 {(x -  \frac{1}{x}) }^{3}  =  {7}^{3}

 {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} }  - 21 = 343

 {x}^{3}  -  \frac{1}{ {x}^{3} }   = 343 + 21

 {x}^{3}  -  \frac{1}{ {x}^{3} }   =3 64

Similar questions