Chapter 2: Problem 61
Write the quotient in standard form. $$\frac{i}{(4-5 i)^{2}}$$
Short Answer
Expert verified
The quotient in standard form is \(\frac{5}{41}+\frac{4}{41}i\).
Step by step solution
01
Identify the Conjugate
We start by identifying the conjugate of the denominator. The conjugate of a complex number a+bi is a-bi. Therefore, the conjugate of 4-5i is 4+5i.
02
Multiply by the Conjugate
We then multiply both the numerator and denominator by the conjugate of the denominator. This gives us: \(\frac{i(4+5i)}{(4-5i)(4+5i)}\).
03
Simplify the Expression
After multiplication, we simplify the expression to get a standard form of the complex number. The multiplication of (4-5i)(4+5i) gives 41. Applying foil method to the numerator yields 4i + 5. Simplifying gives us: \(\frac{4i + 5}{41}\).
04
Write in standard form a + bi
To write the quotient in standard form a + bi, parse the real and imaginary parts. This allows us to rewrite the expression as: \(\frac{5}{41}+\frac{4}{41}i\)
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Standard Form
Standard form for complex numbers refers to the format expressed as \(a + bi\), where \(a\) is the real part and \(b\) is the imaginary part. This form makes it easy to perform operations on complex numbers.
Here's why it's useful:
Always aim to have your final complex number in this format for simplicity and consistency.
Here's why it's useful:
- Clarity: Having a structured form helps to clearly identify the real and imaginary components.
- Operations: It simplifies addition, subtraction, and comparison of complex numbers.
- Graphing: Standard form makes it easier to plot on the complex plane, where the real part is the x-coordinate and the imaginary part is the y-coordinate.
Always aim to have your final complex number in this format for simplicity and consistency.
Complex Conjugate
The complex conjugate of a complex number \(a + bi\) is \(a - bi\). This simple transformation plays a crucial role in operations involving complex numbers.
- Purpose: It is used to eliminate the imaginary part of a denominator in a fraction, thereby simplifying division involving complex numbers.
- Property: Multiplying a complex number by its conjugate results in a real number. For example, \((4-5i)(4+5i) = 41\).
FOIL Method
The FOIL method is a technique used primarily to expand two binomials. It stands for First, Outer, Inner, Last, representing the pairs of terms multiplied together.
For a product of two binomials, such as \((x + y)(a + b)\), apply the FOIL steps:
In our problem, the numerator \(i(4 + 5i)\) was expanded using the FOIL method:
For a product of two binomials, such as \((x + y)(a + b)\), apply the FOIL steps:
- First: Multiply the first terms from each binomial together, \(x \cdot a\).
- Outer: Multiply the two outer terms, \(x \cdot b\).
- Inner: Multiply the two inner terms, \(y \cdot a\).
- Last: Multiply the last terms from each binomial, \(y \cdot b\).
In our problem, the numerator \(i(4 + 5i)\) was expanded using the FOIL method:
- First: \(i \cdot 4 = 4i\)
- Outer: \(i \cdot 5i = 5i^2 = -5\) (since \(i^2 = -1\))
- Inner and Last: These do not apply here directly, as one term is nullified by previous multiplication.