If α and β are the roots of the quadratic equation x 2 + x + 1 = 0 , then the equation whose roots…

If α and β are the roots of the quadratic equation x2+x+1=0, then the equation whose roots are α2021,β2021 is given by ______
  1. x2-x+1=0
  2. x2+x-1=0
  3. x2-x-1=0
  4. x2+x+1=0

Solution

For quadratic equation, x2+x+1=0

x=-1±1-42=-1±3i2

α=-1+3i2, β=-1-3i2

By using cube roots of unity, we can say α=ω &  β=ω2

So, α2021=ω2021=ω3673.ω2=ω2, as ω3=1

β2021=ω22021=ω31347.ω=ω

Therefore, roots of new equation will be ω, ω2,

Therefore, equation is x2-ω+ω2x+ω.ω2=0

We know, 1+ω+ω2=0 & ω3=1

x2+x+1=0 is the required equation.

Asked in: AP EAMCET 2021 (20 Aug Shift 1)

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