Question

x-1/x=3 then value of x3 -1/x3

Answer 1

Answer :

36

Step-by-step explanation :

x - 1 / x = 3

On cubing both sides ;

( x - 1 / x ) = ( 3 )³

Using Identity :

( a - b )³ = a³ - b³ - 3 ab ( a - b )

⇒ x³ - 1 / x³ - 3 ( x - 1 / x ) = 27

⇒ x³ - 1 / x³ - 3 ( 3 ) = 27

⇒ x³ - 1 / x³ - 9 = 27

⇒ x³ - 1 / x³ = 27 + 9

⇒ x³ - 1 / x³ = 36

Hence, the answer is 36.

Answer 2

Here is the answer, hope it helps..