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Complex Numbers and Quadratic Equations · Question 30

JEE Main 2026 (Online) 22nd January Morning ShiftNumericalMedium📈 Topic in 16% papers+4
1

Let = -1 + i 32 and = -1 - i 32, i = -1. If (7 - 7 + 9 )20 + (9 + 7 - 7 )20 + (-7 + 9 + 7 )20 + (14 + 7 + 7 )20 = m10, then m is

Answer

49

Solution

= , = 2, where 1 + + 2 = 0 and 3 = 1

Put 2 = -1 - :

z1 = 7 - 7 + 9 2 = -2 - 16

z2 = 9 + 7 - 7 2 = 16 + 14

z3 = -7 + 9 + 7 2 = -14 + 2

z4 = 14 + 7( + 2) = 14 - 7 = 7

Now z1 = -2 - 16 2 = -2 + 16 + 16 = 16 + 14 = z2

and 2 z1 = z2 = 16 + 14 2 = -14 + 2 = z3

z120 + z220 + z320 = z120(1 + 20 + 40)

= z120(1 + 2 + ) = 0

m10 = 720 = 4910

m = 49

Answer: 49

JEE Main 2026 (Online) 22nd January Morning Shift

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