Chapter 8: Problem 15
Write each expression in terms of \(i\). $$\sqrt{-16}$$
Short Answer
Expert verified
The expression \(\sqrt{-16}\) can be written as \(4i\).
Step by step solution
01
Understand Complex Numbers
A complex number is a number in the form of \(a + bi\), where \(a\) and \(b\) are real numbers and \(i\) is the imaginary unit. The imaginary unit \(i\) has the property that \(i^2 = -1\). This exercise requires us to express the given number involving a square root of a negative number using \(i\).
02
Apply the Definition of Imaginary Unit
We start by recognizing that \(\sqrt{-1} = i\). The given problem is to find \(\sqrt{-16}\), which can be expressed as the product \(\sqrt{-1} \times \sqrt{16}\).
03
Simplify the Expression
We know that \(\sqrt{16} = 4\). Therefore, \(\sqrt{-16} = \sqrt{-1} \times \sqrt{16} = i \times 4\).
04
Multiply to Write in Standard Form
Multiply the known values: \(4 imes i = 4i\). Therefore, \(\sqrt{-16}\) in the form of \(a + bi\) becomes \(0 + 4i\), which simplifies to \(4i\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Imaginary Unit
The imaginary unit, represented as \(i\), is a fundamental concept in complex numbers. Although the term 'imaginary' might sound like these numbers don't exist, they play a crucial role in mathematics.
- The imaginary unit is defined by its unique property: \(i^2 = -1\).
- This definition is manipulated to help solve equations where square roots of negative numbers appear.
Square Roots of Negative Numbers
Square roots, in general, are numbers which produce a specified product when multiplied by themselves. However, when it comes to negative numbers, things become a bit more challenging.
- Historically, square roots of negative numbers were considered impossible since no real number squared gives a negative result.
- With the introduction of the imaginary unit, we can now compute and understand the square roots of negative numbers.
- First, recognize that \(-16\) can be split into \(-1\times 16\).
- The square root of \(-16\) then becomes \(\sqrt{-1}\times \sqrt{16}\).
- Thanks to \(i\), you know \(\sqrt{-1} = i\), thus transforming \(\sqrt{-16}\) into \(4i\), since \(\sqrt{16} = 4\).
Expressions Involving i
Once familiar with \(i\), you can construct expressions involving this unit to deal with complex problems. These expressions use \(i\) to express numbers that include imaginary parts.
- Typically, complex numbers are written in the form \(a + bi\), where \(a\) is the real part, and \(bi\) is the imaginary part.
- In our example, \(\sqrt{-16}\), the result simplifies to \(4i\). Here, \(a = 0\) and \(b = 4\).
- Combine like terms, just like you would with algebraic expressions.
- Be mindful of multiplying \(i\) because \(i \times i = i^2 = -1\).
- Simplify to achieve the typical form of a complex number.