SSC CGL 2018 PYQ — Question 20

SSC CGL Tier II Quant - 17/02/2018 • Quantitative Aptitude • Q20

If α and β are the roots of the equation x2 - x + 1 = 0, then which equations will have roots α3 and β3?

Show answer & explanation

Correct answer: A

Explanation

The correct answer is option 1 i.e. x2 + 2x + 1 = 0.

x2 - x + 1 = 0

αβ = 1

α + β = 1

Cubing on both sides 

α3 + β3 + 3αβ (α + β) = 1

α3 + β3 + 3(1)(1) = 1

α3 + β3 = -2

α3 β3 = 1

Required equation = x2 + 2x + 1 = 0