Question

if the value of x+1/x=5 then the value of x³+1/x³ is

a) 110
b) 90
c) 80
d) 50​

Answer 1

Answer:

Hey Hi

The answer is 110

Hope this helps

For any doubt comment below

Regards

Rishabh Bansal

Answer 2

Given:

$</p><p> \rightarrow \: \sf \quad \left( x + \frac{1}{x} \right) = 5</p><p>$

To Find:

$</p><p> \sf \rightarrow \: \quad \left( {x}^{3} + \frac{1}{ {x}^{3} } \right)</p><p>$

Solution:

$</p><p> \rightarrow \: \quad \sf x + \frac{1}{x} = 5 \\ \\ \rightarrow \: \quad \sf \left(x + \frac{1}{x} \right)^{3} = {5}^{3} \\ \\ \rightarrow \: \quad \sf {x}^{ 3} + \frac{1}{ {x}^{3} } + 3 \cdot \cancel{x} \cdot \frac{1}{ \cancel{x}} (x + \frac{1}{x} ) = 125 \\ \\ \rightarrow \: \quad \sf {x}^{3} + \frac{1}{ {x}^{3} } + 3 \cdot 5 = 125 \: \qquad \left( \because \: x + \frac{1}{x} = 5 \right) \\ \\ \rightarrow \: \quad \sf {x}^{3} + \frac{1}{ {x}^{3} } = 125 - 15 \\ \\ \rightarrow \: \quad \sf {x}^{3} + \frac{1}{ {x}^{3} } = 110</p><p>$