Answer
$$3+4i$$
Work Step by Step
$(2 +i)^2 =(2 +i)(2 +i) $
Multiply using FOIL - First Outer Inner Last
$4 +2i+2i+i^2$
Since $i^2 = -1$:
$4 + 4i + (-1)$
Remember that standard form is $a+bi$
$$3 + 4i$$
Precalculus (6th Edition)
by Lial, Margaret L.; Hornsby, John; Schneider, David I.; Daniels, Callie
Published by
Pearson
ISBN 10:
013421742X
ISBN 13:
978-0-13421-742-0
Chapter 1 - Equations and Inequalities - 1.3 Complex Numbers - 1.3 Exercises - Page 112: 60
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