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Ch. 1 - Equations and Inequalities
Lial - College Algebra 13th Edition
Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook
Chapter 2, Problem 55a

Find each product. Write answers in standard form. (2+i)(3-2i)

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Recall that to multiply two complex numbers, use the distributive property (FOIL method): multiply each term in the first complex number by each term in the second complex number.
Write the expression explicitly: \((2 + i)(3 - 2i) = 2 \cdot 3 + 2 \cdot (-2i) + i \cdot 3 + i \cdot (-2i)\).
Calculate each product: \(2 \cdot 3 = 6\), \(2 \cdot (-2i) = -4i\), \(i \cdot 3 = 3i\), and \(i \cdot (-2i) = -2i^2\).
Remember that \(i^2 = -1\), so replace \(-2i^2\) with \(-2(-1) = 2\).
Combine like terms: add the real parts \(6 + 2\) and the imaginary parts \(-4i + 3i\) to write the product in standard form \(a + bi\).

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Complex Numbers

Complex numbers are numbers in the form a + bi, where a and b are real numbers and i is the imaginary unit with the property i² = -1. They extend the real number system and are used to represent quantities involving the square root of negative numbers.
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Multiplication of Complex Numbers

To multiply complex numbers, use the distributive property (FOIL method) to expand the product, then combine like terms. Remember to apply i² = -1 to simplify terms involving i², converting them into real numbers.
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Standard Form of a Complex Number

The standard form of a complex number is a + bi, where a is the real part and b is the imaginary part. After multiplication, simplify the expression to this form by combining real and imaginary terms separately.
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