Question

if x2 -3x+1 = 0 , then x3 + 1/x3 is equal to ???

Answer 1

Answer:

Step-by-step explanation:

Hello there,

The answer to your question is in the attached pic.

Please refer the pic for step-by-step explanation.

Answer is 18.

Hope you find my answer useful.

Harith

Maths AryaBhatta

Answer 2

Answer:

18

Step-by-step explanation:

Given,

$x^2-3x+1=0$

$x^2+1=3x$

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

By cubing both sides,

$(x+\frac{1}{x})^3=27$

$x^3+(\frac{1}{x})^3+3x\times \frac{1}{x}\times (x+\frac{1}{x})=27$

$x^3+\frac{1}{x^3}+3(x+\frac{1}{x})=27$

$x^3+\frac{1}{x^3}+3\times 3=27$ ( From equation (1) )

$x^3+\frac{1}{x^3}+9=27$

$x^3+\frac{1}{x^3}=18$

Which is the required answer.