lProwid%3D1168028#question7 ing er Magni fier Highlight mode Q Zoom in Q Zo out Review later 7. Elizabeth tried to find the product of (2 + 4i) and (3 – i), and her work is shown below. Identify the error in the process shown and determine the correct product of (2 + 4i) and (3- i). A 面 Gi (2+4i)(3 – i) = 6-2i+12i-4;? = 6+10i – 4 = 6+10i -4(1) = 6+10i -4 = 2+10i

Algebra and Trigonometry (6th Edition)
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ISBN:9780134463216
Author:Robert F. Blitzer
Publisher:Robert F. Blitzer
ChapterP: Prerequisites: Fundamental Concepts Of Algebra
Section: Chapter Questions
Problem 1MCCP: In Exercises 1-25, simplify the given expression or perform the indicated operation (and simplify,...
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### Problem Statement

Elizabeth tried to find the product of \((2 + 4i)\) and \((3 - i)\), and her work is shown below. Identify the error in the process shown and determine the correct product of \((2 + 4i)\) and \((3 - i)\).

### Work Shown

\[
(2 + 4i)(3 - i)
\]

\[
= 6 - 2i + 12i - 4i^2
\]

\[
= 6 + 10i - 4i^2
\]

\[
= 6 + 10i - 4(1)
\]

\[
= 6 + 10i - 4
\]

\[
= 2 + 10i
\]

### Explanation

Elizabeth's error occurs in the treatment of \(i^2\). Recall that \(i^2 = -1\), not \(1\).

### Correct Calculation

Re-evaluate using the property \(i^2 = -1\):

\[
= 6 - 2i + 12i - 4i^2
\]

\[
= 6 + 10i - 4(-1)
\]

\[
= 6 + 10i + 4
\]

\[
= 10 + 10i
\]

Thus, the correct product is \(10 + 10i\).
Transcribed Image Text:### Problem Statement Elizabeth tried to find the product of \((2 + 4i)\) and \((3 - i)\), and her work is shown below. Identify the error in the process shown and determine the correct product of \((2 + 4i)\) and \((3 - i)\). ### Work Shown \[ (2 + 4i)(3 - i) \] \[ = 6 - 2i + 12i - 4i^2 \] \[ = 6 + 10i - 4i^2 \] \[ = 6 + 10i - 4(1) \] \[ = 6 + 10i - 4 \] \[ = 2 + 10i \] ### Explanation Elizabeth's error occurs in the treatment of \(i^2\). Recall that \(i^2 = -1\), not \(1\). ### Correct Calculation Re-evaluate using the property \(i^2 = -1\): \[ = 6 - 2i + 12i - 4i^2 \] \[ = 6 + 10i - 4(-1) \] \[ = 6 + 10i + 4 \] \[ = 10 + 10i \] Thus, the correct product is \(10 + 10i\).
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