Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Algebra

Question:

If $x^2-3 x+1=0$, then what is the value of $x^6+\frac{1}{x^6}$ ?

Options:

324

322

318

327

Correct Answer:

322

Explanation:

x4 + x2y2 + y4 = (x– xy + y2) (x2 + xy + y2)

If $K+\frac{1}{K}=n$

then, $K^2+\frac{1}{K^2}$ = n2 – 2

If x + \(\frac{1}{x}\)  = n

then, $x^3 +\frac{1}{x^3}$ = n3 - 3 × n

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

then what is the value of $x^6+\frac{1}{x^6}$

Divide If $x^2-3 x+1=0$, by x on both the sides,

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

x2 + \(\frac{1}{x^2}\) =  32 – 2 = 7

cubing both the sides,

$x^6 +\frac{1}{x^6}$ = 73 - 3 × 7 = 322