Dividing Complex Numbers

Dividing complex numbers is similar to dividing rational expressions with a radical in the denominator (which requires rationalization of the denominator). To divide Complex Numbers multiply the numerator and the denominator by the complex conjugate of the denominator (this is called rationalizing) and simplify.

Example 1:

8 1+i

8 1+i (1-i) (1-i)

multiply numerator and denominator by the complex conjugate of the denominator

The complex conjugate of 1 + i is 1 - i (change the sign in the middle)

8-8i 1-i+i- i 2

use distributive property to eliminate parentheses

8-8i 1- i 2

combine like terms in the denominator

8-8i 1-(-1)

replace imaginary numbers with exponents with the simplest form

(remember that i2 = -1)

8-8i 2

simplify

8 2 - 8i 2

write in a + bi form

4 - 4i

reduce fractions if possible

Example 2:

3+i 3-i

3+i 3-i (3+i) (3+i)

multiply numerator and denominator by the complex conjugate of the denominator

The complex conjugate of 3 - i is 3 + i (change the sign in the middle)

9+3i+3i+ i 2 9+3i-3i- i 2

use distributive property to eliminate parentheses

9+6i+ i 2 9- i 2

Simplify numerator and denominator separately

9+6i+(-1) 9-(-1)

replace imaginary numbers with exponents with the simplest form

( i2 = -1)

8+6i 10

simplify

8 10 + 6i 10

write in a + bi form

4 5 + 3 5 i

reduce fractions if possible

Dividing with complex numbers is easier than it looks. Just remember to work each step without trying to jump ahead. The main thing to remember is to begin by rationalizing the denominator (multiplying the numerator and the denominator by the complex conjugate of the denominator).

Related Links:
Math
algebra
Complex Numbers
Operations With Complex Numbers
Rationalizing Imaginary Denominators

Identifying Real and Imaginary Numbers Quiz
Adding Complex Numbers Quiz
Subtracting Complex Numbers Quiz
Multiplying Complex Numbers. Quiz
Dividing Complex Numbers Quiz
Mixed Complex Number. Quiz


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