Chapter 6: Problem 6
Determine whether each complex number is real or imaginary and write it in the standard form \(a+b i\). $$ -3 i+\sqrt{6} $$
Short Answer
Expert verified
\(\sqrt{6} - 3i\); General complex number
Step by step solution
01
Identify the Real Part
The real part of a complex number is the term without the imaginary unit \(i\). Look at the given complex number \(-3i + \sqrt{6}\). The real part here is \sqrt{6}\.
02
Identify the Imaginary Part
The imaginary part of a complex number is the term with the imaginary unit \(i\). In the given complex number \(-3i + \sqrt{6}\), the imaginary part is \(-3\), since it is multiplied by \(i\).
03
Write in Standard Form
A complex number in standard form is written as \(a + bi\), where \a\ and \b\ are real numbers. From the previous steps: \a = \sqrt{6} \ and \b = -3.\ Hence, the standard form is \[ \sqrt{6} - 3i \].
04
Determine if Real or Imaginary
A complex number is purely real if its imaginary part \(b\) is zero and purely imaginary if its real part \(a\) is zero. Since \b \ is \ -3 \ (not zero) and \a \ is \sqrt{6}\ (not zero), the given number is neither purely real nor purely imaginary; it is a general complex number.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Real Part of a Complex Number
For any complex number, the real part is the term that does not involve the imaginary unit \(i\). When we look at a complex number written as \(a + bi\), where \(a\) and \(b\) are real numbers, the real part is simply \(a\). To identify the real part in the complex number \(-3i + \sqrt{6}\), we need to find the term that does not include \(i\). Here, it is clearly \(\sqrt{6}\). The real part helps us to understand how the complex number behaves on a real number line, without involving the imaginary component.
Examples can be helpful:
Examples can be helpful:
- In \(4 + 5i\), the real part is 4.
- In \(-2.7 + 3.1i\), the real part is -2.7.
Imaginary Part of a Complex Number
The imaginary part of a complex number is the term that includes the imaginary unit \(i\). For a complex number written in the form \(a + bi\), the imaginary part is simply \(b\), which is the coefficient of \(i\). To identify the imaginary part in the complex number \(-3i + \sqrt{6}\), we look for the term attached to \(i\). Here, it's \(-3\) since this term is multiplied by \(i\).
This negative sign indicates the direction of the imaginary part along the imaginary axis.
Examples for clarity:
This negative sign indicates the direction of the imaginary part along the imaginary axis.
Examples for clarity:
- In \(4 + 5i\), the imaginary part is 5.
- In \(3 - 2i\), the imaginary part is -2.
- In \(-3i + \sqrt{6}\), the imaginary part is -3.
Standard Form of a Complex Number
The standard form of a complex number is expressed as \(a + bi\), where \(a\) is the real part and \(b\) is the imaginary part. Writing a complex number in this form ensures clarity, making both its real and imaginary parts evident.
Using our example, \(-3i + \sqrt{6}\):
Remember, the standard form is consistent: even if either \(a\) or \(b\) is zero, it's still written in the form \(a + bi\). For instance:
Using our example, \(-3i + \sqrt{6}\):
- The real part \(a\) is \(\sqrt{6}\).
- The imaginary part \(b\) is \(-3\).
Remember, the standard form is consistent: even if either \(a\) or \(b\) is zero, it's still written in the form \(a + bi\). For instance:
- If a complex number is purely real, like \(5\): It is written as \(5 + 0i\).
- If it is purely imaginary, like \(-2i\): It appears as \(0 - 2i\).