JEE Main · Mathematics ↓ Falling

Complex Numbers appeared 41 times across 3 years — 4.7% of Mathematics. This question is from Properties of Moduli.

Year 2026 2025 2024 Total
Questions 11 16 14 41

Let z = (1 + i)(1 + 2i)(1 + 3i) (1 + ni), where i = √(-1). If |z|² = 44200, then n is equal to

Numerical Answer Type:
Enter a numerical value Answer: 5 to 5 +4 marks

Solution & Explanation

Related Formula
|z₁ · z₂ zₙ| = |z₁| · |z₂| |zₙ| |1 + ri|² = 1² + r² = 1 + r²
Core Logic

Given z = Πr=1ⁿ (1 + ri). Take the modulus of both sides:

|z| = Πr=1ⁿ |1 + ri|

Square both sides:

|z|² = Πr=1ⁿ |1 + ri|² = Πr=1ⁿ (1 + r²)
Step 1: Factoring the Target Number

We are given |z|² = 44200. Factorizing 44200:

44200 = 442 × 100 = (2 × 221) × (10²) = 2 × (13 × 17) × (2² × 5²) = 2³ · 5² · 13 · 17
Step 2: Expanding the Product

Calculate the product series step-by-step for small values of n: For r=1: 1 + 1² = 2 For r=2: 1 + 2² = 5 For r=3: 1 + 3² = 10 = 2 × 5 For r=4: 1 + 4² = 17 For r=5: 1 + 5² = 26 = 2 × 13

Now, multiply these first 5 terms together:

P₅ = 2 × 5 × 10 × 17 × 26 = 2 × 5 × (2 × 5) × 17 × (2 × 13) = 2³ × 5² × 13 × 17
Step 3: Comparing and Concluding

The calculated product for n=5 exactly matches the prime factorization of 44200. Therefore, n = 5.

Pattern Recognition

Modulus is multiplicative. In problems featuring chains of complex multiplications set equal to a huge real magnitude, instantly switch to magnitudes and map to integer factorization.

Chapter Mix

Class 11 Maths: Complex Numbers

Properties of Moduli diagram for Q23 - JEE Main 2026 Evening
Properties of Moduli diagram for Q23 - JEE Main 2026 Evening

Reference Study Guides

More Complex Numbers Previous-Year Questions — Page 9

Q26 jee_main_2024_31_jan_morning Properties of Modulus and Argument
If α denotes the number of solutions of |1 - i|^x = 2^x and β = ((|z|)/( (z))), where z = (π)/(4) (1 + i)⁴ ( 1 - √(π) i√(π) + i + √(π) - i1 + √(π) i), i = √(-1), then the distance of the point (α, β) from the line 4x - 3y = 7 is
Numerical Answer. Answer: 3 to 3

Solution

Core Logic
|1 - i|^x = 2^x (√(2))^x = 2^x 2x/2 = 2^x

This implies (x)/(2) = x x = 0. There is exactly 1 solution, so α = 1.

Step 1: Simplify complex number z
(1+i)⁴ = ((1+i)²)² = (1 + i² + 2i)² = (2i)² = -4

Thus, z = -π ( (1-√(π)i)(√(π)-i)π + 1 + (√(π)-i)(1-√(π)i)1 + π )

Step 2: Simplify Bracket

Let's expand the terms directly: z = (π)/(4)(-4) [ √(π) - π i - i - √(π)π + 1 + √(π) - i - π i - √(π)1 + π ]

= -π [ (-i(π+1))/(π+1) + (-i(π+1))/(π+1) ] = -π [ -i - i ] = 2π i
Step 3: Find beta

For z = 2π i: |z| = 2π and (z) = (π)/(2).

β = (|z|)/( (z)) = (2π)/(π/2) = 4
Step 4: Distance from Line

Distance of point (α, β) = (1, 4) from the line 4x - 3y - 7 = 0:

D = |4(1) - 3(4) - 7|√(4² + (-3)²) = (|4 - 12 - 7|)/(5) = (|-15|)/(5) = 3
Chapter Mix

Class 11 Maths: Complex Numbers and Quadratic Equations Class 11 Maths: Straight Lines

More Complex Numbers Questions — jee_main_2026_24_january_evening

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