introduction

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Introduction Recall that the imaginary unit i is equal to . A fraction with i in the denominator does not have a rational denominator, since is not a rational number. Similar to rationalizing a fraction with an irrational square root in the denominator, fractions with i in the denominator can also have the denominator rationalized. 1 4.3.4: Dividing Complex Numbers

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Introduction Recall that the imaginary unit i is equal to . A fraction with i in the denominator does not have a rational denominator , since is not a rational number. - PowerPoint PPT Presentation

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Page 1: Introduction

IntroductionRecall that the imaginary unit i is equal to . A fraction with i in the denominator does not have a rational denominator, since is not a rational number. Similar to rationalizing a fraction with an irrational square root in the denominator, fractions with i in the denominator can also have the denominator rationalized.

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4.3.4: Dividing Complex Numbers

Page 2: Introduction

Key Concepts• Any powers of i should be simplified before dividing

complex numbers. • After simplifying any powers of i, rewrite the division of

two complex numbers in the form a + bi as a fraction. • To divide two complex numbers of the form a + bi and

c + di, where a, b, c and d are real numbers, rewrite the quotient as a fraction.

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4.3.4: Dividing Complex Numbers

Page 3: Introduction

Key Concepts, continued• Rationalize the denominator of a complex fraction by

using multiplication to remove the imaginary unit i from the denominator.

• The product of a complex number and its conjugate is a real number, which does not contain i.

• Multiply both the numerator and denominator of the fraction by the complex number in the denominator.

• Simplify the rationalized fraction to find the result of the division.

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4.3.4: Dividing Complex Numbers

Page 4: Introduction

Key Concepts, continued• In the following equation, let a, b, c, and d be real

numbers.

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4.3.4: Dividing Complex Numbers

Page 5: Introduction

Common Errors/Misconceptions• multiplying only the denominator by the complex

conjugate • incorrectly determining the complex conjugate of the

denominator

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4.3.4: Dividing Complex Numbers

Page 6: Introduction

Guided PracticeExample 2Find the result of (10 + 6i ) ÷ (2 – i ).

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4.3.4: Dividing Complex Numbers

Page 7: Introduction

Guided Practice: Example 2, continued1. Rewrite the expression as a fraction.

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4.3.4: Dividing Complex Numbers

Page 8: Introduction

Guided Practice: Example 2, continued2. Find the complex conjugate of the

denominator. The complex conjugate of a – bi is a + bi, so the complex conjugate of 2 – i is 2 + i.

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4.3.4: Dividing Complex Numbers

Page 9: Introduction

Guided Practice: Example 2, continued3. Rationalize the fraction by multiplying

both the numerator and denominator by the complex conjugate of the denominator.

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4.3.4: Dividing Complex Numbers

Page 10: Introduction

Guided Practice: Example 2, continued4. If possible, simplify the fraction. The

answer can be left as a fraction, or simplified by dividing both terms in the numerator by the quantity in the denominator.

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4.3.4: Dividing Complex Numbers

Page 11: Introduction

Guided Practice: Example 2, continued

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4.3.4: Dividing Complex Numbers

Page 12: Introduction

Guided PracticeExample 3Find the result of (4 – 4i) ÷ (3 – 4i

3).

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4.3.4: Dividing Complex Numbers

Page 13: Introduction

Guided Practice: Example 3, continued1. Simplify any powers of i.

i 3 = –i

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4.3.4: Dividing Complex Numbers

Page 14: Introduction

Guided Practice: Example 3, continued2. Simplify any expressions containing a

power of i. 3 – 4i

3 = 3 – 4(–i) = 3 + 4i

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4.3.4: Dividing Complex Numbers

Page 15: Introduction

Guided Practice: Example 3, continued3. Rewrite the expression as a fraction, using

the simplified expression. Both numbers should be in the form a + bi.

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4.3.4: Dividing Complex Numbers

Page 16: Introduction

Guided Practice: Example 3, continued4. Find the complex conjugate of the

denominator. The complex conjugate of a + bi is a – bi, so the complex conjugate of 3 + 4i is 3 – 4i.

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4.3.4: Dividing Complex Numbers

Page 17: Introduction

Guided Practice: Example 3, continued5. Rationalize the fraction by multiplying

both the numerator and denominator by the complex conjugate of the denominator.

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4.3.4: Dividing Complex Numbers

Page 18: Introduction

Guided Practice: Example 3, continued6. If possible, simplify the fraction. The

answer can be left as a fraction, or simplified by dividing both terms in the numerator by the quantity in the denominator.

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4.3.4: Dividing Complex Numbers

Page 19: Introduction

Guided Practice: Example 3, continued

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4.3.4: Dividing Complex Numbers