Chapter 8: Problem 71
Find the following quotients. Write all answers in standard form for complex numbers. $$\frac{5-2 i}{i}$$
Short Answer
Expert verified
The quotient is \( 2 + 5i \).
Step by step solution
01
Set up the expression
Given the expression \( \frac{5 - 2i}{i} \), our goal is to express this quotient in standard form \( a + bi \), where \( a \) and \( b \) are real numbers.
02
Multiply by the conjugate of the denominator
The conjugate of \( i \) is \( -i \). Multiply both the numerator and denominator by \( -i \) to eliminate the imaginary unit in the denominator: \[ \frac{(5 - 2i)(-i)}{i(-i)} \].
03
Simplify the denominator
Simplify the denominator using the property that \( i^2 = -1 \): \( i(-i) = i^2 = -1 \). Thus, the denominator becomes \(-1\).
04
Distribute and simplify the numerator
Distribute \( -i \) in the numerator:\( (5 - 2i)(-i) = 5(-i) - 2i(-i) = -5i + 2i^2 \).Since \( i^2 = -1 \), this becomes \(-5i + 2(-1) = -5i - 2 \).
05
Simplify the entire expression
The expression now is \( \frac{-5i - 2}{-1} \). Simplify this by dividing each term by \(-1\):\( \frac{-5i}{-1} + \frac{-2}{-1} = 5i + 2 \).So the result in standard form is \( 2 + 5i \).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Complex Numbers Division
Dividing complex numbers might seem challenging at first, but it follows a logical process. When dividing a complex number like \( \frac{5 - 2i}{i} \), the main goal is to remove the imaginary unit \( i \) from the denominator. This process requires multiplication by the conjugate.
- **Identify the denominator**: In this exercise, the denominator is simply \( i \).
- **Find the conjugate**: The conjugate of \( i \) is \( -i \), because multiplying \( i \) by \(-i\) results in \( i^2 = -1 \), removing the imaginary unit.
- **Multiply the numerator and the denominator by the conjugate**: Perform the multiplication to keep the expression equivalent but without \( i \) in the denominator.
Standard Form of Complex Numbers
After handling the division, the next step is to ensure the result is in standard form, which is \( a + bi \).
- **Understand the form**: For complex numbers, standard form means having a real part \( a \) and an imaginary part \( bi \).
- **Simplifying the expression**: If the division or any other operation results in non-standard form, you'll need to collect terms.
Simplifying Complex Expressions
Simplifying complex expressions is crucial for clearer results and easier understanding of complex numbers.
- **Distribute accurately**: Make sure each part of the binomial gets multiplied correctly when expanding. For example, with \( (5 - 2i)(-i) \), each term must interact with \(-i\).
- **Use \( i^2 = -1 \) appropriately**: This property turns imaginary terms into real values when combined in pairs.
- **Combine like terms**: After distribution and substitution with \( i^2 = -1 \), sum up the real terms separately from the imaginary terms.