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Complex Numbers and Quadratic Equations · Question 54

JEE Main 2025 (Online) 2nd April Morning ShiftMCQEasy📈 Topic in 26% papers+4−1
1

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

Answer

(1) x2 + x - 1 = 0

Solution

+ = P1 = 1

P10 = ( + )P9 - P8 10 + 10 = ( + )( 9 + 9) - ( 8 + 8)

123 = 76 - 47 = -1

For roots 1 , 1 :

Sum = + = 1-1 = -1, Product = 1 = -1

x2 - (-1)x + (-1) = 0 x2 + x - 1 = 0

Answer: (1)

JEE Main 2025 (Online) 2nd April Morning Shift

Keep practising — Complex Numbers and Quadratic Equations

2

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 .

JEE Main 2025 (Online) 2nd April Evening Shift
3

The number of solutions of the equation ( 9x - 9 x + 2 ) ( 2x - 7 x + 3 ) = 0 is :

  1. 3
  2. 2
  3. 1
  4. 4
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4

Let |z1 - 8 - 2i| 1 and |z2 - 2 + 6i| 2, z1, z2 C. Then the minimum value of |z1 - z2| is :

  1. 3
  2. 10
  3. 7
  4. 13
JEE Main 2025 (Online) 29th January Morning Shift
5

The sum, of the squares of all the roots of the equation x2 + |2x - 3| - 4 = 0, is

  1. 6(2 - 2)
  2. 3(3 - 2)
  3. 3(2 - 2)
  4. 6(3 - 2)
JEE Main 2025 (Online) 28th January Morning Shift
6

Let O be the origin, the point A be z1 = 3 + 2 2i, the point B(z2) be such that 3|z2| = |z1| and (z2) = (z1) + 6. Then

  1. area of triangle ABO is 114
  2. area of triangle ABO is 11 3
  3. ABO is a scalene triangle
  4. ABO is an obtuse angled isosceles triangle
JEE Main 2025 (Online) 28th January Morning Shift
7

If + i and + i are the roots of x2 - (3 - 2i)x - (2i - 2) = 0, i = -1, then + is equal to:

  1. 2
  2. -6
  3. 6
  4. -2
JEE Main 2025 (Online) 28th January Evening Shift

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