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

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

Multiplying Complex Numbers: (4 + 3i)(2 - 5i)

This article will explore the process of multiplying two complex numbers, specifically (4 + 3i)(2 - 5i).

Understanding Complex Numbers

A complex number is a number that can be expressed in the form a + bi, where a and b are real numbers, and i is the imaginary unit, defined as the square root of -1 (i² = -1).

Multiplying Complex Numbers

To multiply complex numbers, we use the distributive property, similar to how we multiply binomials in algebra.

  1. Distribute: (4 + 3i)(2 - 5i) = 4(2 - 5i) + 3i(2 - 5i)

  2. Simplify: = 8 - 20i + 6i - 15i²

  3. Substitute i² with -1: = 8 - 20i + 6i - 15(-1)

  4. Combine real and imaginary terms: = (8 + 15) + (-20 + 6)i

  5. Final result: = 23 - 14i

Therefore, the product of (4 + 3i) and (2 - 5i) is 23 - 14i.

Visualizing Complex Numbers

Complex numbers can be visualized on a complex plane, where the horizontal axis represents the real part and the vertical axis represents the imaginary part. Multiplying complex numbers can be viewed as a geometric transformation on this plane.

Conclusion

Multiplying complex numbers involves applying the distributive property and simplifying the expression by substituting with -1. The resulting product is also a complex number, expressed in the form a + bi. Understanding complex number multiplication is crucial in various fields like electrical engineering, physics, and mathematics.

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