Precalculus: Mathematics for Calculus, 7th Edition

Published by Brooks Cole
ISBN 10: 1305071751
ISBN 13: 978-1-30507-175-9

Chapter 1 - Section 1.6 - Complex Numbers - 1.6 Exercises - Page 64: 34


$(3-7i)(3+7i) = 58$

Work Step by Step

1. $(3-7i)(3+7i)$ 2.Use the difference of two squares formula $a2−b2=(a+b)(a−b)$ (or Multiply the two binomials together (use the FOIL method to distribute the First, Outer, Inner, and Last terms)): $9-49i^{2}$ 3. Change $-49i^{2}$ to 49, because $i^{2} = -1$ and $-49\times-1 = 49$:$9+49$ 4. Add the two numbers together: 58
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