Question

if
$x - \frac{1}{x} = 5$
find the value of
$x {}^{3} + \frac{1}{x} {}^{3}$
​

Answer 1

Step-by-step explanation:

Here,

x + 1/x = 5

then,

x³ + 1/x³ = ?

According to formula ,

a³ + b³ = ( a + b)³ - 3ab( a+ b)

x³ + 1/x³ = ( x + 1/x) ³ - 3 . x . 1/x ( x + 1/x)

= ( 5)³ - 3 × 5

= 125 - 15

= 110 answer