Chapter 5: Problem 54
Simplify. $$ \sqrt{-13} \cdot \sqrt{-26} $$
Short Answer
Expert verified
\(-\sqrt{338}\)
Step by step solution
01
Understand the Expression
We are asked to simplify the expression \( \sqrt{-13} \cdot \sqrt{-26} \). Here, both numbers under the square root are negative, which means we will deal with imaginary numbers. The square root of a negative number involves the imaginary unit \( i \), where \( i = \sqrt{-1} \).
02
Express the Square Roots Using the Imaginary Unit
Rewrite \( \sqrt{-13} \) as \( \sqrt{13} \cdot i \) and \( \sqrt{-26} \) as \( \sqrt{26} \cdot i \). So the expression becomes \( (\sqrt{13} \cdot i) \cdot (\sqrt{26} \cdot i) \).
03
Simplify the Expression
Use the property \( i^2 = -1 \) to simplify. The expression \((\sqrt{13} \cdot i) \cdot (\sqrt{26} \cdot i) \) becomes \( \sqrt{13} \cdot \sqrt{26} \cdot i^2 \).
04
Calculate the Square Roots and Multiply
Calculate the multiplication of the square roots: \( \sqrt{13} \cdot \sqrt{26} = \sqrt{13 \times 26} = \sqrt{338} \).
05
Apply the Imaginary Unit Condition
Since \( i^2 = -1 \), multiply \( \sqrt{338} \) with \( i^2 \) to get \(-\sqrt{338} \). This is because multiplying by \( i^2 \) introduces the negative sign.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Complex Numbers
Complex numbers are a fundamental concept in mathematics that expand our understanding beyond real numbers by introducing an imaginary component. A complex number is often expressed in the form \( a + bi \), where:
- \( a \) is the real part of the number
- \( b \) is the imaginary part, and
- \( i \) represents the imaginary unit, satisfying \( i^2 = -1 \).
Square Roots
The square root of a number \( x \) is a value that, when multiplied by itself, gives \( x \). For positive numbers, this is straightforward. However, the introduction of square roots of negative numbers calls for special treatment.
For instance, computing \( \sqrt{-13} \) involves using the imaginary unit \( i \) such that \( i = \sqrt{-1} \). The process follows these steps:
For instance, computing \( \sqrt{-13} \) involves using the imaginary unit \( i \) such that \( i = \sqrt{-1} \). The process follows these steps:
- Take the square root of the positive equivalent, \( \sqrt{13} \).
- Multiply it by \( i \) to express the negative number's square root as \( \sqrt{13} \cdot i \).
Properties of i
The imaginary unit \( i \) has unique properties that simplify working with square roots of negative numbers. Understanding these properties is essential:
- \( i = \sqrt{-1} \)
- \( i^2 = -1 \)
- \( i^3 = -i \)
- \( i^4 = 1 \), and the cycle repeats every four powers.