Question

if x+1/x=9, then find x³ +1/x³​

Answer 1

$x + \frac{1}{x } = 9$

$cubing \: on \: both \: sides$

$(x + \frac{1}{x} {})^{3} = {9}^{3}$

${x}^{3} + ( { \frac{1}{x} })^{3} + 3.x. \frac{1}{x} (x + \frac{1}{x} ) = 729$

${x}^{3} + \frac{1}{ {x}^{3} } = 702$

${x}^{3} + ( { \frac{1}{x} })^{3} + 27 = 729$