PREPARING Become a MATIZEN What is Math Planet ? A Crash Course on      Algebra A Crash Course on      Geometry   EXPLORING Advanced Math Topic Customized Lessons SAT & ACT Reviews   INTERACTING Math Games Discussion Forum Math Live! Chat   COLLECTING Math Search MATIZEN Qualifi-      -cation Test Acknowledgements The Creatures Behind      the Math Planet        ©1998 ThinkQuest        team 16284    All rights reserved

Chapter 4: Quadratic Equations

  Absolute Value of a Complex Number: The absolute value of a complex number a + bi is |a + bi| = Ö (a² + b²)

  When comes to calculating one or more complex numbers, we use the following formulas:

  Addition of Complex Numbers: For all real numbers a, b. c, and d, (a + bi) + (c + di) = (a + c) + (b + d)i.

  The Additive Inverse Property of Complex Numbers: For each complex number z, there is a complex number - z such that z + ( - z) = 0. If z = a + bi, then - z = - (a + bi) = - a - bi.

  Subtraction of Complex Numbers: For all complex numbers w and z, w - z = w + (- z).

  If w = a + bi and z = c + di, then w - z = (a + bi) - (c + di) = (a – c) + (b + d)i

  Complex Conjugates: For all real numbers a and b, a + bi and a - bi are complex conjugates.

  Multiplication of Complex Numbers: For all complex numbers a + bi and c + di, (a + bi)(c + di) = (ac - bd) + (ad + bc)i.

    Quadratic equations are very useful in solving many problems and equations.  If you can learn quadratic equations well, you will do well on all kinds of problems.   Please take a few minutes break and click here to continue to the next chapter. (You can also click on the drop-down list below to jump to any chapter you like.)

You can also jump to the chapter of your choice by using the drop-down list at below.