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Section 7.5 Complex Numbers and Solving Quadratic Equations with Complex Solutions.

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Presentation on theme: "Section 7.5 Complex Numbers and Solving Quadratic Equations with Complex Solutions."— Presentation transcript:

1 Section 7.5 Complex Numbers and Solving Quadratic Equations with Complex Solutions

2 The Imaginary Number i The imaginary number i is defined as. So: Objective 1: Express complex numbers in standard form.

3 Notice that any power of i can be simplified to i, 1, i, or 1. Simplify each power of i

4 If a and b are real numbers and, then: Algebraic FormNumerical Example is a complex number with a ____________ term a and an ____________ term bi. has a real term ______ and an imaginary term ______. Complex Numbers

5 Simplify each expression and write the result in the standard form. 7.8.

6 Simplify each expression and write the result in the standard form

7 Simplify each expression and write the result in the standard form

8 Simplify each expression and write the result in the standard form. 13.

9 Simplify each expression and write the result in the standard form. 14.

10 Simplify each expression and write the result in the standard form. 15.

11 Objective 2: Add, subtract, multiply, and divide complex numbers.

12 Addition of Binomials Addition of Complex Numbers The arithmetic of complex numbers is very similar to the arithmetic of binomials

13 16. Simplify each expression and write the result in the standard form.

14 17. Simplify each expression and write the result in the standard form.

15 18. Simplify each expression and write the result in the standard form.

16 19. Simplify each expression and write the result in the standard form.

17 20. Simplify each expression and write the result in the standard form.

18 21. Simplify each expression and write the result in the standard form.

19 22. Simplify each expression and write the result in the standard form.

20 23. Simplify each expression and write the result in the standard form.

21 Complex Conjugates: The conjugate ofis Write the conjugate of each expression. Then multiply the expression by its conjugate. ExpressionConjugate Product 24.

22 Complex Conjugates: The conjugate ofis Write the conjugate of each expression. Then multiply the expression by its conjugate. ExpressionConjugate Product 25.

23 Dividing Complex Numbers - The fact that the product of a complex number and its conjugate is always a real number plays a key role in the division of complex numbers as outlined in the following box.

24 Steps for Dividing Complex Numbers Step 1. Write the division problem as a fraction. Step 2. Multiply both the numerator and the denominator by the conjugate of the denominator. Step 3. Simplify the result, and express it in standard form. Example

25 26. Perform the indicated operations and express the result in form.

26 27. Perform the indicated operations and express the result in form.

27 28. Perform the indicated operations and express the result in form.

28 29. Perform the indicated operations and express the result in form.

29 30. Determine whether or not is a solution of the equation

30 31. Determine whether or not is a solution of the equation

31 Objective 3: Solve a quadratic equation with imaginary solutions Recall solving quadratic equations by extraction of roots from Section 7.1: The solutions of are and

32 Solve each quadratic equation by extraction of roots. 32.

33 Solve each quadratic equation by extraction of roots. 33.

34 Solve each quadratic equation by extraction of roots. 34.

35 Solve each quadratic equation by extraction of roots. 35.

36 Solve each quadratic equation by extraction of roots. 36.

37 Solve each quadratic equation by extraction of roots. 37.

38 Recall solving quadratic equations by the Quadratic Formula from Section 7.3: The solutions of the quadratic equation with real coefficients a, b, and c, when are

39 Use the quadratic formula to solve each quadratic equation. 38.

40 39. Use the quadratic formula to solve each quadratic equation.

41 40. Use the quadratic formula to solve each quadratic equation.

42 41. Use the quadratic formula to solve each quadratic equation.

43 42. Use the quadratic formula to solve each quadratic equation. (Hint: Use the zero factor principle.)

44 Construct a quadratic equation in x that has the given solutions. 43. and

45 Construct a quadratic equation in x that has the given solutions. 44.and

46 45. Determine the discriminant of each of these quadratic equations and then determine the solution of each equation. EquationDiscriminantSolution (a)

47 45. Determine the discriminant of each of these quadratic equations and then determine the solution of each equation. Equation DiscriminantSolution (b)

48 45. Determine the discriminant of each of these quadratic equations and then determine the solution of each equation. Equation DiscriminantSolution (c)


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