Roots of Unity

IMPORTANT

Roots of Unity: Overview

This topic covers concepts such as Cube Roots of Unity, Nth Roots of Unity, Finding Roots of a Complex Equation Using Nth Roots of Unity, etc.

Important Questions on Roots of Unity

HARD
IMPORTANT

Let   ω be a complex cube root of unity with   ω1.  A fair die is thrown three times.   r 1 , r 2 and r 3  are the numbers obtained on the die, then the probability that   ω r 1 + ω r 2 + ω r 3 =0 is

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 ­–

EASY
IMPORTANT

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

MEDIUM
IMPORTANT

Let z1,z2,,z7 be the vertices of a regular heptagon that is inscribed in the unit circle with centre at the origin in the complex plane. Let w=1i<j7zizj, then w is equal to

EASY
IMPORTANT

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

MEDIUM
IMPORTANT

If z=32+i2 i=-1,  then 1+iz+z5+iz89 is equal to:

EASY
IMPORTANT

If  ω is a complex cube root of unity (not equal to 1), and ( 1+ω ) 7 =A+Bω , then real numbers A and B are respectively ­_____:

MEDIUM
IMPORTANT

If 1ω, ω2,ωn-1 are n, nth roots of unity, then the then the value 9-ω9-ω29-ω39-ωn-1 is

EASY
IMPORTANT

If ω is an imaginary cube root of unity than -1--1--1-to  can be equal to

EASY
IMPORTANT

If i=-1, then 4+5-12+i32334+3 -12+i32365 is equal to

EASY
IMPORTANT

Let, zk (k=0, 12, ..6) be the roots of the equation z+17+z7=0, then k=06Re(zk) is equal to

EASY
IMPORTANT

If z+1z+1=0, then z2003+1z2003 is equal to 

HARD
IMPORTANT

Let w1 and w13=1, then find the Quadratic equation whose roots are w+w3+w4+w-4+w-3+w-1 and w2+w5+w6+w-6+w-5+w-2

EASY
IMPORTANT

Evaluate 1+ω-ω27, where ω is an imaginary cube root of unity.

MEDIUM
IMPORTANT

Let ω be a complex number such that 2ω+1=z where z=-3 . If

1111-ω2-1ω21ω2ω7=3k,

Then k can be equal to:

MEDIUM
IMPORTANT

If α, βC are the distinct roots of the equation x2-x+1=0, then α101+β107 is equal to

HARD
IMPORTANT

If the cube roots of unity are 1,w,w2, then the roots of the equation x-13+8=0 are

EASY
IMPORTANT

The value of a+bω+cω2b+cω+aω2+a+bω+cω2c+aω+bω2 will be: (ω is non real cube root of unity and expression is well defined)