Roots of Unity

IMPORTANT

Roots of Unity: Overview

This topic covers concepts, such as, Cube Roots of Unity, Nth Roots of Unity & Common Roots of Complex Equations etc.

Important Questions on Roots of Unity

HARD
IMPORTANT

Let z 1  and   z 2 be nth roots of unity which subtend a right angle at the origin, then n must be of the form -

HARD
IMPORTANT

Let   S=| a+bω+c ω 2 |, where a, b and c are not all equal integers and   ω  is an imaginary cube root of unity. Then minimum value of S is 

EASY
IMPORTANT

If  ω is an imaginary cube root of unity and  (1+ω)7=A+Bω, then real numbers A and B are respectively ­–

MEDIUM
IMPORTANT

Let α, β, γ be the three  roots of the equation x3+bx+c=0 if βγ=1=-α then b3+2c3-3α3-6β3-8γ3 is equal to 

MEDIUM
IMPORTANT

If ω is imaginary cube root of unity, then value of r=0541+ωr+ω2r equals to

MEDIUM
IMPORTANT

If 1,z1,z2,,zn-1 be the nth  roots of unity and 'ω' be a non-real complex cube root of unity, then sum of all possible values of r=1n-1ω-zr will be equal to

MEDIUM
IMPORTANT

Let a be a root of the equation 1+x2+x4 = 0. Then the value of a1011+a2022a3033 is equal to:

MEDIUM
IMPORTANT

The area of triangle whose vertices are z, ωz, z+ωz is (where ω is complex cube root of unity)

EASY
IMPORTANT

If ω is a cube root of unity, then the value of polynomial x+1ωω2ωx+ω21ω21x+ω is

HARD
IMPORTANT

If ω=e-2πi3,a,b,c,x,y,z are non-zero complex numbers such that a+b+c=x,a+bω+cω2=y and a+bω2+cω=z, then x2+y2+z2a2+b2+c2=

MEDIUM
IMPORTANT

The common roots of the equations Z3+2z2+2z+1=0, z2014+z2015+1=0 are

EASY
IMPORTANT

If x2+x+1=0, then -x-1x2+x2-1x22+x3-1x32 is ___________.

EASY
IMPORTANT

If ω is a cube root of unity, then 1+ω2=

HARD
IMPORTANT

If z2+z+1=0, where z is a complex number, find the value of  z+1z2+z2+1z22+z3+1z32+z4+1z42+z5+1z52+z6+1z62.

HARD
IMPORTANT

Find the number of 15th roots of unity, which are also 25th roots of unity.

EASY
IMPORTANT

If 1,ω,ω2 are the cube roots of unity, then find the value of k if  (a+2b)2+aω2+2bω2+aω+2bω22=kab.

EASY
IMPORTANT

If 1,ω,ω2 are the cube roots of unity, then find the value of (2-ω)2-ω22-ω102-ω11 is 

MEDIUM
IMPORTANT

If 1+ω7=A+Bω then

MEDIUM
IMPORTANT

The roots of the equation x3=1 are

EASY
IMPORTANT

If 1, ω, ω2 are three cube roots of unity, then 1-ω+ω23=