How to Solve Complex Numbers – A Simple Guide to Mastering the Basics

How to Solve Complex Numbers A Simple Guide to Mastering the Basics

To solve complex numbers, I first identify their components: the real part and the imaginary part. A complex number is typically expressed as ( a + bi ), where ( a ) is the real part and ( bi ) represents the imaginary part, with ( i ) being the square root of ( -1 ).

I perform operations on complex numbers similarly to how I handle polynomials, keeping in mind that ( $i^2 = -1$ ).

When subtracting or adding complex numbers, I combine the real parts and the imaginary parts separately. For example, when I add ( 2 + 3i ) and ( 4 + 2i ), the result is ( (2+4) + (3i+2i) = 6 + 5i ).

Multiplying complex numbers involves using the distributive property and remembering to replace ( $i^2 v) with ( -1 ) when it appears. Stay tuned to discover how this skill opens up a new dimension of mathematics, one that even explains the seemingly impossible square root of a negative number.

Steps Involved in Solving Complex Numbers

When dealing with complex numbers, we’re working with expressions of the form ( a+bi ), where ( a ) and ( b ) are real numbers, and ( i ) is the imaginary unit with the property that ( $i^2 = -1$ ). Here’s how I approach solving complex numbers in various operations:

Addition of Complex Numbers: To add two complex numbers, I simply add their real parts and their imaginary parts separately.

  • If I have ( (a+bi) + (c+di) ), the result is ( (a+c) + (b+d)i ).

Subtraction of Complex Numbers: Subtraction follows a similar process as addition.

  • For ( (a+bi) – (c+di) ), I find ( (a-c) + (b-d)i ).

Multiplication of Complex Numbers: When multiplying, I apply the distributive property and remember that ($ i^2 = -1$ ).

  • For ( (a+bi)(c+di) ), this expands to ( $ac + adi + bci + bdi^2 $), which simplifies to ( (ac-bd) + (ad+bc)i ).

Division of Complex Numbers: To divide by a complex number, I multiply the numerator and denominator by the conjugate of the denominator.

  • To divide ( $\frac{a+bi}{c+di}$ ), I multiply by the conjugate ($ \frac{c-di}{c-di} ), resulting in ( \frac{(ac+bd) + (bc-ad)i}{c^2+d^2} $).

Here’s a quick reference table for these operations:

Addition( (a+bi) + (c+di) )( (a+c) + (b+d)i )
Subtraction( (a+bi) – (c+di) )( (a-c) + (b-d)i )
Multiplication( (a+bi)(c+di) )( (ac-bd) + (ad+bc)i )
Division($ \frac{a+bi}{c+di}$ )( $\frac{(ac+bd) + (bc-ad)i}{c^2+d^2} $)

To simplify complex numbers, I make sure to group real parts and imaginary parts and reduce them to their simplest form. Plotting complex numbers on a complex plane with the real number on the x-axis and the imaginary on the y-axis helps visualize these computations.

The Complex Plane and Magnitude

In the study of complex numbers, I find it essential to understand the complex plane, which provides a visual representation of these numbers.

Illustration of The Complex Plane and Magnitude

Each complex number takes the form of $a + bi$, where $a$ is the real component, $b$ is the imaginary component, and $i$ is the imaginary unit defined by $i^2 = -1$.

Real numbers are positioned along the horizontal axis (often called the x-axis), while imaginary numbers fall along the vertical axis (referred to as the y-axis). This two-dimensional plane is what I call the complex plane.

Here’s a brief table to illustrate this concept:

ExpressionReal Part (a)Imaginary Part (b)Notation on Complex Plane
$3 + 4i$34(3, 4)
$-2 – 5i$-2-5(-2, -5)
$0 + 2i$02(0, 2)
$-7$-70(-7, 0)

To communicate distance and size, complex numbers use magnitude, which resembles the absolute value for real numbers. The magnitude, or absolute value, of a complex number represents its distance from the origin (0,0) in the complex plane. I calculate the magnitude of a complex number $z = a + bi$ using the formula:

$$|z| = \sqrt{a^2 + b^2}$$

The magnitude connects algebra to geometry, allowing me to measure the distance from the origin to any point $(a, b)$ in the plane. If I interpret complex numbers in terms of vectors, magnitude represents the vector’s length.

A complex number’s magnitude has a relationship with angle, or direction, from the positive side of the real axis, forming a polar coordinate system that offers another perspective for working with complex numbers.

Advanced Concepts in Complex Numbers

When examining complex numbers further, I quickly encounter the concept of the complex conjugate. For any complex number ( z = a + bi ), its conjugate is ( $\overline{z} = a – bi $). The conjugate has an essential property: multiplying a complex number by its conjugate gives a real number, specifically ($ z \overline{z} = a^2 + b^2 $).

Looking at polynomials with complex coefficients, particularly binomials, I often use the quadratic formula. For a quadratic equation ( ax^2 + bx + c = 0 ), where ( a ), ( b ), and ( c ) are real numbers, and ($ a \neq 0$ ), the roots are given by:

$ x = \frac{-b \pm \sqrt{b^2 – 4ac}}{2a}$

When ( b^2 – 4ac < 0 ), square roots of negative numbers appear, leading to complex solutions.

For visual understanding, the Mandelbrot set is a striking representation of complex numbers, reflecting the behavior of quadratic polynomials iteratively applied to complex numbers. Points within this set are bound in size, no matter how many iterations I run.

Here’s a brief look at operations involving complex conjugates:

Conjugation($ \overline{z} $)( a – bi )
Multiplication( $z \overline{z} $)($ a^2 + b^2$ )
Division( $\frac{z}{\overline{z}}$ )($ \frac{z \overline{z}}{a^2 + b^2} = \frac{a^2 + b^2}{a^2 + b^2} = 1 ) (if ( z \neq 0 )$)

To explore these concepts practically, I may look at binomials of the form ( (a+bi)(c+di) ) and expand them to see complex number interactions.

In all my explorations with complex numbers, I find their properties have profound implications in fields ranging from engineering to theoretical physics, far beyond the initial imaginings when they were conceived.

Applications and Visualization

In the realm of electronics, complex numbers are quite practical. I like to visualize them on what we call the complex plane, where I interpret the real part of a complex number as the x-coordinate (horizontal axis) and the imaginary part as the y-coordinate (vertical axis). This standard form, ( a + bi ), is where ( a ) represents the real part and ( bi ) represents the imaginary part, with ( i ) being the imaginary unit.

When we multiply complex numbers, the FOIL method (First, Outer, Inner, Last) is helpful:

Given two complex numbers:

$\begin{align*} z_1 &= a + bi \ z_2 &= c + di \end{align*} $

Their product is: $\begin{align*} z_1 \cdot z_2 &= (a + bi)(c + di) \ &= ac + adi + bci + bdi^2 \ &= (ac – bd) + (ad + bc)i \end{align*} $

Pure imaginary numbers are of the form ( bi ) where ( b ) is a real number, and these lie purely on the vertical axis of the complex plane.

When it comes to online resources, domains like and are powerful because they bypass the web filter, meaning that I can freely access a plethora of educational content to understand complex numbers better.

Standard Form( a + bi )
Pure ImaginaryLies on the imaginary axis, of the form ( bi )
MultiplicationUse FOIL: ( (a + bi)(c + di) )
VisualizationPlot on the complex plane with real and imaginary axes

It’s key to remember that the ability to visualize complex numbers offers a geometric understanding of operations like addition, where vectors are combined, or multiplication, which involves rotating and scaling these vectors on the complex plane.


In this article, I’ve provided you with the fundamental techniques required to solve complex numbers. You’ve learned that a complex number denoted as $a + bi$, is composed of both a real component $a$ and an imaginary component $bi$, where $i$ represents $\sqrt{-1}$. I’ve shown that understanding the conjugate of a complex number, given by $a – bi$, is crucial in processes such as division.

What I find most intriguing about complex numbers is their applicability across various fields, from engineering to physics. They provide solutions to equations that would otherwise have no real solution, such as $x^2 = -1$. Remember, complex numbers can also be represented graphically on a plane, with the real part $a$ on the horizontal axis and the imaginary part $b$ on the vertical axis.

I encourage you to further explore complex numbers and their operations—addition, subtraction, multiplication, and division—as these form the backbone of many advanced mathematical concepts. Mastery of these basics opens the door to understanding more intricate mathematical theories and solving complex problems.

My parting thought to you is to keep practicing. With complex numbers, practice is essential. Just as you learned to perform arithmetic with real numbers, you can become equally proficient with complex numbers through consistent practice and application.