Chapter 10: Problem 69
Perform each indicated operation. Write the result in the form \(a+b i\) $$ (\sqrt{3}+2 i)(\sqrt{3}-2 i) $$
Short Answer
Expert verified
The result is \(7 + 0i\).
Step by step solution
01
Recognize the expression format
Observe that the expression \((\sqrt{3} + 2i)(\sqrt{3} - 2i)\) is in the form of \((a+bi)(a-bi)\), where \(a = \sqrt{3}\) and \(b = 2\). This is a difference of squares, which simplifies to \(a^2 - b^2\).
02
Apply the difference of squares
Use the identity \((a+bi)(a-bi) = a^2 - (bi)^2\). In this case, substitute \(a = \sqrt{3}\) and \(b = 2\) into the formula: \((\sqrt{3})^2 - (2i)^2\).
03
Calculate each square
Calculate \((\sqrt{3})^2 = 3\) and \((2i)^2 = 4i^2\). Recall that \(i^2 = -1\), so \(4i^2 = 4(-1) = -4\).
04
Simplify the expression
Simplify the expression using the results from Step 3: \((\sqrt{3})^2 - (2i)^2 = 3 - (-4)\). Therefore, the expression simplifies to \(3 + 4 = 7\).
05
Express in the form \(a + bi\)
Since the imaginary part is zero, express the result as \(7 + 0i\). This is in the form \(a + bi\), where \(a = 7\) and \(b = 0\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Difference of Squares
The difference of squares is a powerful algebraic identity. It shows how to calculate the product of two conjugates. A conjugate pair can be written as
- a + b and a - b
- terms are conjugates: \((\sqrt{3} + 2i)(\sqrt{3} - 2i)\)
Imaginary Unit
In mathematics, the imaginary unit is represented by the symbol \(i\). It stands for the square root of
- -1
- of \(2i\)
- \((2i)^2 = 4i^2\).
Simplification
Simplification involves making an expression easier to understand.
- The expression \((\sqrt{3})^2 - (2i)^2\) was simplified using basic arithmetic and properties of the imaginary unit.
- \((\sqrt{3})^2 = 3\)
- \((2i)^2 = 4i^2 = 4(-1) = -4\)
- 3 minus -4 equals 7.
- combining like terms
Algebraic Expressions
Algebraic expressions combine numbers, variables, and operations. They form the foundation of algebraic solutions. In our scenario with
- complex numbers
- \(\sqrt{3} + 2i\)
- Recognizing familiar patterns (like difference of squares).
- Handling the imaginary unit so it simplifies computations.