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Intermediate Algebra – Student Workbook – Second Edition 2013

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Lesson 5b - Solving Quadratic Equations<br />

Mini-Lesson<br />

Problem 9<br />

WORKED EXAMPLE <strong>–</strong> OPERATIONS WITH COMPLEX NUMBERS<br />

Simplify each of the following and write in the form a + bi<br />

a) 16<br />

1<br />

16<br />

b) Note: This is SUBTRACTION and not FOIL.<br />

4 1<br />

(3<br />

2i)<br />

(4 i)<br />

3<br />

2i<br />

4 i<br />

0 4i<br />

1<br />

3i<br />

c)<br />

(2 i)(4<br />

2i)<br />

8 4i<br />

4i<br />

2i<br />

8 2i<br />

2<br />

8 2( 1)<br />

8 2<br />

10 0i<br />

2<br />

Note: This one is FOIL. You can also just enter (2 + i)(4 <strong>–</strong> 2i) on your calculator if you put your<br />

calculator in a + bi mode. To work with i on your calculator, press MODE then change REAL to<br />

a+bi by using your arrow keys. The i button is on the bottom row.<br />

Problem<br />

10<br />

MEDIA EXAMPLE <strong>–</strong> OPERATIONS WITH COMPLEX NUMBERS<br />

Simplify each of the following and write in the form a + bi. To work with i on your calculator,<br />

press MODE then change REAL to a+bi by using your arrow keys. The i button is on the bottom<br />

row.<br />

a) (2 <strong>–</strong> 3i) <strong>–</strong> (4 + 2i) =<br />

b) 4i(5 <strong>–</strong> 2i) =<br />

c) (2 <strong>–</strong> i)(1 + i) =<br />

Scottsdale Community College Page 224 <strong>Intermediate</strong> <strong>Algebra</strong>

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