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Complex Numbers and Quadratic Equations · Question 8

JEE Main 2026 (Online) 4th April Morning ShiftMCQMedium📈 Topic in 26% papers+4−1
1

If the set of all solutions of |x2+x-9|=|x|+|x2-9| is [ , ] [ , ), then ( 2+ 2+ 2 ) is equal to:

  1. 9
  2. 18
  3. 36
  4. 72

Answer

(2) 18

Solution

Write x2+x-9=x+(x2-9). So the equation is |a+b|=|a|+|b| with a=x, b=x2-9.

|a+b|=|a|+|b| ab 0

x(x2-9) 0 x(x-3)(x+3) 0

Sign scheme (critical points -3, 0, 3): the product is 0 for -3 x 0 and for x 3.

Solution set =[-3, 0] [3, )

=-3, =0, =3

2+ 2+ 2=9+0+9=18

Answer: (2)

JEE Main 2026 (Online) 4th April Morning Shift

Keep practising — Complex Numbers and Quadratic Equations

2

Let z be a complex number such that |z+2|=|z-2| and ( z+3z-i )= 4. Then |z|2 is equal to:

  1. 9
  2. 4
  3. 5
  4. 1
JEE Main 2026 (Online) 4th April Morning Shift
3

Let S=\z C : z2+4z+16=0\. Then z S |z+ 3 i |2 is equal to :

  1. 42
  2. 23
  3. 27
  4. 38
JEE Main 2026 (Online) 4th April Evening Shift
4

If the quadratic equation ( +2)x2-3 x+4 =0, -2, has two positive roots, then the number of possible integral values of is :

  1. 1
  2. 2
  3. 3
  4. 4
JEE Main 2026 (Online) 4th April Evening Shift
5

Let , +2, Z, be the roots of the quadratic equation x(x+2)+(x+1)(x+3)+(x+2)(x+4)+ +(x+n-1)(x+n+1)=4n for some n N. Then n+ is equal to :

  1. 0
  2. 1
  3. 2
  4. 3
JEE Main 2026 (Online) 2nd April Morning Shift
6

Let x and y be real numbers such that 50 ( 2x1+3i- y1-2i )=31+17i, i= -1. Then the value of 10(x-3y) is :

  1. 20
  2. 31
  3. 35
  4. 75
JEE Main 2026 (Online) 2nd April Morning Shift
7

Let , be the roots of the equation x2-3x+r=0, and 2, 2 be the roots of the equation x2+3x+r=0. If the roots of the equation x2+6x=m are 2 + +2r and -2 - r2, then m is equal to :

  1. -135
  2. -567
  3. 135
  4. 567
JEE Main 2026 (Online) 2nd April Evening Shift
8

Let the circles C1 : |z|=r and C2 : |z-3-4i|=5, z C, be such that C2 lies within C1. If z1 moves on C1, z2 moves on C2 and |z1-z2|=2, then |z1-z2| is equal to :

  1. 12
  2. 17
  3. 22
  4. 24
JEE Main 2026 (Online) 2nd April Evening Shift
9

If α, β, where α < β, are the roots of the equation x2 - ( + 3)x + 3 = 0 such that 1 - 1 = 13, then the sum of all possible values of λ is

  1. 2
  2. 6
  3. 8
  4. 4
JEE Main 2026 (Online) 28th January Morning Shift
10

Let S = \x3 + ax2 + bx + c : a, b, c N and a, b, c 20\ be a set of polynomials. Then the number of polynomials in S, which are divisible by x2 + 2, is

  1. 6
  2. 120
  3. 20
  4. 10
JEE Main 2026 (Online) 28th January Morning Shift
11

Let z be a complex number such that |z − 6| = 5 and |z + 2 − 6i| = 5. Then the value of z3 + 3z2 - 15z + 141 is equal to :

  1. 61
  2. 37
  3. 42
  4. 50
JEE Main 2026 (Online) 28th January Morning Shift

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