Complex numbers blend real and imaginary parts, written as a... Show more
Algebra 247 views·Updated May 21, 2026·3 pagesMastering Operations with Complex Numbers: Add, Subtract, Multiply & Divide
Ahmed AK.@ahmed_ak.
1 / 3
1
of 3
Understanding Complex Numbers
Complex numbers have two parts: a real number and an imaginary number written as a + bi. The mysterious i is defined as the square root of -1, something you can't find on a regular number line!
Working with complex numbers isn't as scary as it sounds. When adding or subtracting, you simply combine like terms - real parts with real parts, imaginary parts with imaginary parts.
For example, to add + , you combine the real parts (5-5) and the imaginary parts to get 0+6i, or simply 6i.
Quick Tip: Think of complex numbers like combining apples and oranges - you can't mix them directly, but you can count how many of each you have!
2
of 3
The Powers of i
When working with complex numbers, understanding the pattern of i raised to different powers is super helpful. The pattern cycles every four powers!
When i is squared (i²), we get -1, because i × i = √-1 × √-1 = -1. This is the foundation for all other powers. For i³, we multiply i² × i, getting -1 × i = -i. Then i⁴ = i² × i² = (-1)(-1) = 1.
The pattern continues: i⁵ = i, i⁶ = -1, i⁷ = -i, i⁸ = 1, and so on. This creates a repeating cycle of four values: i, -1, -i, 1.
Remember This: The powers of i follow a simple pattern: i, -1, -i, 1. If you need to find a higher power, divide the exponent by 4 and look at the remainder!
3
of 3
Multiplying Complex Numbers
Multiplying complex numbers requires applying the pattern of i powers. When you multiply expressions with i, remember that i² equals -1.
Let's try an example: (3) + (4i). First, multiply 3 by each term in to get 6-21i. Then multiply 4i by each term in to get 8i-28i².
Since i² equals -1, we can rewrite 28i² as 28(-1) or -28. Combining all terms: 6-21i+8i+28 = 34-13i.
Pro Tip: When multiplying complex numbers, distribute first just like with regular algebraic expressions, then substitute i² = -1, i³ = -i, and i⁴ = 1 wherever needed!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Similar Content
Most popular content in Algebra 2
9Most popular content
9Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user
Algebra 247 views·Updated May 21, 2026·3 pagesMastering Operations with Complex Numbers: Add, Subtract, Multiply & Divide
Ahmed AK.@ahmed_ak.
Complex numbers blend real and imaginary parts, written as a + bi, where i = √-1. They're a powerful mathematical tool that extends beyond real numbers, allowing us to solve equations that previously seemed impossible.
1
of 3Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Understanding Complex Numbers
Complex numbers have two parts: a real number and an imaginary number written as a + bi. The mysterious i is defined as the square root of -1, something you can't find on a regular number line!
Working with complex numbers isn't as scary as it sounds. When adding or subtracting, you simply combine like terms - real parts with real parts, imaginary parts with imaginary parts.
For example, to add + , you combine the real parts (5-5) and the imaginary parts to get 0+6i, or simply 6i.
Quick Tip: Think of complex numbers like combining apples and oranges - you can't mix them directly, but you can count how many of each you have!
2
of 3Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
The Powers of i
When working with complex numbers, understanding the pattern of i raised to different powers is super helpful. The pattern cycles every four powers!
When i is squared (i²), we get -1, because i × i = √-1 × √-1 = -1. This is the foundation for all other powers. For i³, we multiply i² × i, getting -1 × i = -i. Then i⁴ = i² × i² = (-1)(-1) = 1.
The pattern continues: i⁵ = i, i⁶ = -1, i⁷ = -i, i⁸ = 1, and so on. This creates a repeating cycle of four values: i, -1, -i, 1.
Remember This: The powers of i follow a simple pattern: i, -1, -i, 1. If you need to find a higher power, divide the exponent by 4 and look at the remainder!
3
of 3Sign up to see the content. It's free!
- Access to all documents
- Improve your grades
- Join milions of students
Multiplying Complex Numbers
Multiplying complex numbers requires applying the pattern of i powers. When you multiply expressions with i, remember that i² equals -1.
Let's try an example: (3) + (4i). First, multiply 3 by each term in to get 6-21i. Then multiply 4i by each term in to get 8i-28i².
Since i² equals -1, we can rewrite 28i² as 28(-1) or -28. Combining all terms: 6-21i+8i+28 = 34-13i.
Pro Tip: When multiplying complex numbers, distribute first just like with regular algebraic expressions, then substitute i² = -1, i³ = -i, and i⁴ = 1 wherever needed!
We thought you’d never ask...
What is the Knowunity AI companion?
Our AI companion is specifically built for the needs of students. Based on the millions of content pieces we have on the platform we can provide truly meaningful and relevant answers to students. But its not only about answers, the companion is even more about guiding students through their daily learning challenges, with personalised study plans, quizzes or content pieces in the chat and 100% personalisation based on the students skills and developments.
Where can I download the Knowunity app?
You can download the app in the Google Play Store and in the Apple App Store.
Is Knowunity really free of charge?
That's right! Enjoy free access to study content, connect with fellow students, and get instant help – all at your fingertips.
Similar Content
Most popular content in Algebra 2
9Most popular content
9Can't find what you're looking for? Explore other subjects.
Students love us — and so will you.
4.6/5App Store
4.7/5Google Play
The app is very easy to use and well designed. I have found everything I was looking for so far and have been able to learn a lot from the presentations! I will definitely use the app for a class assignment! And of course it also helps a lot as an inspiration.
Stefan SiOS user
This app is really great. There are so many study notes and help [...]. My problem subject is French, for example, and the app has so many options for help. Thanks to this app, I have improved my French. I would recommend it to anyone.
Samantha KlichAndroid user
Wow, I am really amazed. I just tried the app because I've seen it advertised many times and was absolutely stunned. This app is THE HELP you want for school and above all, it offers so many things, such as workouts and fact sheets, which have been VERY helpful to me personally.
AnnaiOS user