## Algebra 2 (1st Edition)

Published by McDougal Littell

# Chapter 4 Quadratic Functions and Factoring - 4.6 Perform Operations with Complex Numbers - 4.6 Exercises - Skill Practice - Page 280: 57

#### Answer

The solution is not written in standard form, $a+bi$. The correct answer is $6+7i$

#### Work Step by Step

The solution is not written in standard form, $a+bi$. Using $i^{2}=-1$, we correct the error. $(1+2i)(4-i)$ $=4-i+8i-2i^{2}$ $=-2i^{2}+7i+4$ $=-2(-1)+7i+4\qquad$ ...simplify $=2+7i+4\qquad$ ...simplify $=6+7i$

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