Question

x+1/x=5 finc x^3+1/x^3=?

Answer 1

Answer:

115

Step-by-step explanation:

$x + \frac{1}{x} = 5$

${(x + \frac{1}{x} )}^{2} = 25$

${x}^{2} + \frac{1}{ {x}^{2} } + 2 = 25$

${x}^{2} + \frac{1}{ {x}^{2} } = 23$

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

${5}^{3} = {x}^{3} + \frac{1}{ {x}^{3} } + 3(5)$

$125 = {x}^{3} + \frac{1}{ {x}^{3} } + 15$

${x}^{3} + \frac{1}{ {x}^{3} } = 115$

Hope it helps