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Complex Numbers and Quadratic Equations · Question 45

JEE Main 2025 (Online) 4th April Morning ShiftMCQEasy📈 Topic in 10% papers+4−1
1

Consider the equation x2 + 4x - n = 0, where n [20, 100] is a natural number. Then the number of all distinct values of n, for which the given equation has integral roots, is equal to

  1. 6
  2. 5
  3. 8
  4. 7

Answer

(1) 6

Solution

Roots: x = -4 16 + 4n2 = -2 4 + n

Roots are integers ⇔ 4 + n is a perfect square.

∵ 20 n 100 ⇒ 24 4 + n 104

⇒ 4 + n = 25, 36, 49, 64, 81, 100

⇒ n = 21, 32, 45, 60, 77, 96

∴ Number of values of n = 6

Answer: (1)

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Keep practising — Complex Numbers and Quadratic Equations

2

Let A = \z C : |z - 2 - i| = 3\, B = \z C : Re(z - iz) = 2\ and S = A B. Then z S |z|2 is equal to .

JEE Main 2025 (Online) 4th April Morning Shift
3

Let the product of 1 = (8 + i) + (7 + 4i) and 2 = (1 + 8i) + (4 + 7i) be + i , i = -1. Let p and q be the maximum and the minimum values of + respectively. Then p + q is equal to :

  1. 130
  2. 150
  3. 160
  4. 140
JEE Main 2025 (Online) 4th April Evening Shift
4

If is a root of the equation x2+x+1=0 and k=1n ( k+ 1 k )2=20, then n is equal to .

JEE Main 2025 (Online) 4th April Evening Shift
5

Let and be the roots of x2 + 3x - 16 = 0, and and be the roots of x2 + 3x - 1 = 0. If Pn = n + n and Qn = n + n, then P25 + 3P242P23 + Q25 - Q23Q24 is equal to

  1. 4
  2. 3
  3. 5
  4. 7
JEE Main 2025 (Online) 3rd April Morning Shift
6

Let z C be such that z2+3iz-2+i = 2+3i. Then the sum of all possible values of z2 is :

  1. -19+2i
  2. -19-2i
  3. 19-2i
  4. 19+2i
JEE Main 2025 (Online) 3rd April Morning Shift
7

If z1, z2, z3 C are the vertices of an equilateral triangle whose centroid is z0, then k=13 (zk - z0)2 is equal to

  1. 0
  2. 1
  3. i
  4. -i
JEE Main 2025 (Online) 3rd April Evening Shift
8

Let the equation x(x + 2)(12 - k) = 2 have equal roots. Then the distance of the point (k, k2 ) from the line 3x + 4y + 5 = 0 is

  1. 15
  2. 12
  3. 5 3
  4. 15 5
JEE Main 2025 (Online) 3rd April Evening Shift
9

Let z be a complex number such that |z| = 1. If 2 + k2 zk + z = kz, k R, then the maximum distance of k + ik2 from the circle |z - (1 + 2i)| = 1 is :

  1. 5 + 1
  2. 3
  3. 3 + 1
  4. 2
JEE Main 2025 (Online) 2nd April Morning Shift
10

Let Pn = n + n, n N. If P10 = 123, P9 = 76, P8 = 47 and P1 = 1, then the quadratic equation having roots 1 and 1 is :

  1. x2 + x - 1 = 0
  2. x2 - x + 1 = 0
  3. x2 + x + 1 = 0
  4. x2 - x - 1 = 0
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11

If the set of all a R - \1\, for which the roots of the equation (1 - a)x2 + 2(a - 3)x + 9 = 0 are positive is (- , - ] [ , ), then 2 + + is equal to .

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