Find the modulus of z = (1 - i)4 ?

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Agniveer Vayu Science (Group X) 22nd March 2025 Memory-Based Paper
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  1. 2
  2. 4
  3. - 4
  4. None of these

Answer (Detailed Solution Below)

Option 2 : 4
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Detailed Solution

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CONCEPT:

  • i2 = - 1
  • If z = x + iy then \(|z| = \sqrt{x^2 + y^2}\) 

CALCULATION:

Given: z = (1 - i)4 First let's simplify the expression (1 - i)4 

⇒ (1 - i)2 = 1 + i2 - 2i

As we know that, i2 = - 1

⇒ (1 + i)2 = -2i

Since (1 - i)(1 - i)× (1 - i)2 we get:

⇒ (1 + i)4 = (-2i)2 = - 4

⇒ z = - 4 + 0i

As we know that, if z = x + iy then \(|z| = \sqrt{x^2 + y^2}\) 

Here, x = - 4 and y = 0

⇒ \(|z| = \sqrt{(-4)^2 + 0^2} = \pm 4\) 

As we know that, |z| denotes the distance between origin and z in the argand plane. So, |z| cannot be negative

⇒ |z| = 4

Hence, correct option is 2.

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