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In Exercises 13-40, perform the indicated operation, simplify, and express in standard form. $$ (4+7 i)-(5+3 i) $$

Short Answer

Expert verified
The result is \(-1 + 4i\).

Step by step solution

01

Identify the Real and Imaginary Parts

Identify the real and imaginary components of each complex number. For \((4 + 7i)\), the real part is 4, and the imaginary part is \(7i\). For \((5 + 3i)\), the real part is 5, and the imaginary part is \(3i\).
02

Perform the Subtraction on Real Parts

Subtract the real part of the second complex number from the real part of the first complex number: \(4 - 5 = -1\).
03

Perform the Subtraction on Imaginary Parts

Subtract the imaginary part of the second complex number from the imaginary part of the first complex number. In this case, subtract \(3i\) from \(7i\): \(7i - 3i = 4i\).
04

Combine the Results

Combine the results of both subtractions to form the simplified complex number. The real component is \(-1\) and the imaginary component is \(4i\), giving the expression \(-1 + 4i\).
05

Express in Standard Form

Make sure the resulting complex number is in the form \(a + bi\), where \(a\) is the real part and \(bi\) is the imaginary part. The expression \(-1 + 4i\) is already in the standard form of a complex number.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Real Part
In complex numbers, the real part is the component that does not involve the imaginary unit \(i\). Each complex number is typically expressed as \(a + bi\), where \(a\) represents the real part. In our example, the complex number \((4 + 7i)\) has a real part of \(4\). Similarly, in the complex number \((5 + 3i)\), the real part is \(5\).

Understanding the real part is crucial as it allows you to handle complex numbers similarly to real numbers in operations like addition and subtraction. By focusing first on the real components, you can simplify the calculations before moving to the imaginary parts. This makes managing complex numbers more straightforward.

When subtracting complex numbers, you subtract their real parts separately from their imaginary parts to identify each component clearly.
Imaginary Part
The imaginary part of a complex number is the component that involves the imaginary unit \(i\). The imaginary unit \(i\) is unique because it is defined as \(\sqrt{-1}\). Thus, the imaginary part expresses multiples of \(i\).

For the exercises given, in the complex number \((4 + 7i)\), the imaginary part is \(7i\). In \((5 + 3i)\), the imaginary part is \(3i\). This distinction is important because it allows mathematical operations to take the imaginary properties into account without confusion with real number components.

Subtracting imaginary parts can be likened to common algebraic subtraction. For instance, subtracting \(3i\) from \(7i\) results in \(4i\). Handling the imaginary parts separately and then combining them with the real parts ensures that you maintain the distinction needed in complex number operations.
Standard Form
Complex numbers are conventionally expressed in the standard form, which is \(a + bi\). This format clearly separates the real part \(a\) and the imaginary part \(bi\). The standard form is immensely beneficial for understanding and performing mathematical operations on complex numbers.

After performing operations on complex numbers, like addition or subtraction, it is crucial to express the result in standard form. In our example, after subtracting the complex numbers \((4 + 7i)-(5 + 3i)\), we get \(-1 + 4i\). Both parts are expressed to show the real and imaginary components, ensuring that it's in standard form.

By always expressing complex numbers in this clear and consistent manner, it simplifies their manipulation and also facilitates understanding in more complex mathematical contexts. Make sure the structure, \(a + bi\), is held so that each component is easily identifiable for further operations or examinations.

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Most popular questions from this chapter

For Exercises 71 and 72, refer to the following: Spirals are seen in nature-for example, in the swirl of a pine cone. They are also used in machinery to convert motions. An Archimedes spiral has the general equation \(r=a \theta\). A more general form for the equation of a spiral is \(r=a \theta^{1 / n}\), where \(n\) is a constant that determines how tightly the spiral is wrapped. Archimedes Spiral. Compare the Archimedes spiral \(r=\theta\) with the spiral \(r=\theta^{1 / 2}\) by graphing both on the same polar graph.

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