Question

x+1/x=9 then find x³+1/x³​

Answer 1

Answer:

x + 1/x = 9

Since we want x^3 + 1/x^3 let's cube both sides of the given equation.

Now,

(a+b)^3 = a^3 + b^3 + 3ab (a+b)

So,

x+1/x = 9

Cubing both sides

x^3 + 1/x^3 + 3x(1/x)(x+1/x) = 729

So,

x^3 + 1/x^3 + 3(9) = 729

or,

x^3 + 1/x^3 = 729-27 = 702.

Hope this helps you !

Answer 2

Step-by-step explanation:

$x + \frac{1}{x} = 9 \\ ({x + \frac{1}{x}) }^{3} = {x}^{3} + { \frac{1}{x} }^{3} + 3(x + \frac{1}{x} ) \\ {x}^{3} + { \frac{1}{x} }^{3} = 729 - 27 \\ = 702$

therefore ur answer is 702