answersLogoWhite

0

First, let's make sure we are not confusing imaginary numbers with complex numbers.

Imaginary (sometimes called "pure imaginary" for clarity) numbers are numbers of the form ai, where a is a real number and i is the principal square root of -1.

To multiply two imaginary numbers ai and bi, start by pretending that i is a variable (like x).

So ai x bi = abi2. But since i is the square root of -1, i2=-1. So abi2=-ab.

For example, 6i x 7i =-42.

5i x 2i =-10.

(-5i) x 2i =-(-10)= 10.

Complex numbers are numbers of the form a+bi, where a and b are real numbers. a is the real part, bi is the imaginary part.

To multiply two complex numbers, again, just treat i as if it were a variable and then in the final answer, substitute -1 wherever you see i2.

Hence (a+bi)(c+di) = ac + adi + bci + dbi2 which simplifies to ac-db + (ad+bc)i.

For example:

(2+3i)(4+5i) = 8 + 10i +12i + 15i2= 8 + 10i + 12i - 15 = -7 + 22i

User Avatar

Wiki User

15y ago

Still curious? Ask our experts.

Chat with our AI personalities

RafaRafa
There's no fun in playing it safe. Why not try something a little unhinged?
Chat with Rafa
DevinDevin
I've poured enough drinks to know that people don't always want advice—they just want to talk.
Chat with Devin
MaxineMaxine
I respect you enough to keep it real.
Chat with Maxine

Add your answer:

Earn +20 pts
Q: How do you multiply imaginary numbers?
Write your answer...
Submit
Still have questions?
magnify glass
imp
Continue Learning about Basic Math

Imaginary numbers examples?

An imaginary number is a number that cannot exist. An example of an imaginary number would be: the square root of negative nine, or any negative number. When I try to think of any two of the same numbers that would multiply together to be negative nine, all I can think of is 3 or -3. when I square both of those numbers, I get the number 9, not -9. When I multiply two negatives together, I get a positive number, therefore there is no possible way to get the square root of -9, or any negative number.


What is complex math?

Complex math covers how to do operations on complex numbers. Complex numbers include real numbers, imaginary numbers, and the combination of real+imaginary numbers.


What is an imaginary number and how is it expressed?

An imaginary number is a number that cannot exist. An example of an imaginary number would be: the square root of negative nine, or any negative number. When I try to think of any two of the same numbers that would multiply together to be negative nine, all I can think of is 3 or -3. when I square both of those numbers, I get the number 9, not -9. When I multiply two negatives together, I get a positive number, therefore there is no possible way to get the square root of -9, or any negative number.


What numbers are not real numbers?

The square root of any negative number is not a real number. denoted as i for imaginary because it does not exist, in the normal concept of numbers.Complex numbers (which include real and imaginary numbers) are combinations of real & imaginary numbers.While these numbers do not exist in the everyday concept of numbers, they are important in concepts of electricity and waves.


Is Every complex number is a pure imaginary number?

No. All Complex Numbers are of the form a + bi where a and b are Real Numbers and i is the square root of -1. So only ones where a = 0 are pure Imaginary Numbers.