Medium INTEGER +4 / -1 PYQ · JEE Mains 2021

The sum of 162th power of the roots of the equation x3 $-$ 2x2 + 2x $-$ 1 = 0 is ________.

Answer (integer) 3

Solution

x<sup>3</sup> $-$ 2x<sup>2</sup> + 2x $-$ 1 = 0<br><br>x = 1 satisfying the equation<br><br>$\therefore$ x $-$ 1 is factor of <br><br>x<sup>3</sup> $-$ 2x<sup>2</sup> + 2x $-$ 1<br><br>= (x $-$ 1) (x<sup>2</sup> $-$ x + 1) = 0<br><br>x = 1, ${{1 + i\sqrt 3 } \over 2},{{1 - i\sqrt 3 } \over 2}$<br><br>x = 1, $-$ $\omega$<sup>2</sup>, $-$$\omega$<br><br>Sum of 162<sup>th</sup> power of roots<br><br>= (1)<sup>162</sup> + ($-$$\omega$<sup>2</sup>)<sup>162</sup> + ($-$$\omega$)<sup>162</sup><br><br>= 1 + ($\omega$)<sup>324</sup> + ($\omega$)<sup>162</sup><br><br>= 1 + 1 + 1 = 3

About this question

Subject: Mathematics · Chapter: Complex Numbers and Quadratic Equations · Topic: Complex Numbers and Argand Plane

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