(2/1-i+3/1+i)(2+3i/4+5i)

3 min read Jun 16, 2024
(2/1-i+3/1+i)(2+3i/4+5i)

Simplifying Complex Number Expressions

This article will guide you through simplifying the complex number expression:

(2/1-i + 3/1+i)(2+3i/4+5i)

Let's break it down step by step:

1. Simplifying Individual Fractions

First, we need to simplify the fractions within the expression:

  • 2/1-i: To get rid of the complex number in the denominator, we multiply both numerator and denominator by the conjugate of the denominator:
2/1-i * (1+i)/(1+i) = (2+2i)/(1-i^2) = (2+2i)/2 = 1+i 
  • 3/1+i: We follow the same process:
3/1+i * (1-i)/(1-i) = (3-3i)/(1-i^2) = (3-3i)/2 = 1.5-1.5i
  • 2+3i/4+5i: Again, multiply numerator and denominator by the conjugate:
(2+3i)/(4+5i) * (4-5i)/(4-5i) = (8 - 10i + 12i + 15)/(16+25) = (23+2i)/41 

2. Combining Simplified Fractions

Now, our expression becomes:

(1+i + 1.5-1.5i)(23+2i/41)

3. Performing Multiplication

Let's multiply the terms in the first bracket:

(2.5 - 0.5i)(23+2i/41)

Now, we distribute the terms:

(2.5 * 23 + 2.5 * 2i/41 - 0.5i * 23 - 0.5i * 2i/41)

Simplifying:

(57.5 + 5i/41 - 11.5i - i^2/41)

Since i^2 = -1, we substitute:

(57.5 + 5i/41 - 11.5i + 1/41)

4. Final Simplification

Combining real and imaginary terms:

(57.5 + 1/41) + (5/41 - 11.5)i

Finally, we arrive at the simplified form:

57.56 + (-11.44)i

Therefore, the simplified expression of (2/1-i+3/1+i)(2+3i/4+5i) is 57.56 - 11.44i.

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