Chapter 1: Problem 22
Evaluate the expression and write the result in the form \(a+b i .\) $$ (5-3 i)(1+i) $$
Short Answer
Expert verified
The expression evaluates to \(8 + 2i\).
Step by step solution
01
Distribute Terms
Start by applying the distributive property to the expression \((5-3i)(1+i)\). This means we need to multiply each term in the first binomial by each term in the second binomial. This gives us:\[5(1) + 5(i) - 3i(1) - 3i(i)\]
02
Simplify the Real Parts
Next, let's simplify the real parts of the expression obtained from multiplication. The real parts are \(5(1)\) and \(-3i(i)\) which simplifies as follows:\[5 \text{ and } -3i^2\]Since \(i^2 = -1\), we have:\[-3(-1) = 3\]Thus, add the numbers: \[5 + 3 = 8\]
03
Simplify the Imaginary Parts
Now, simplify the imaginary parts of the expression. The imaginary parts are:\[5(i) - 3i(1) = 5i - 3i\]Calculate: \[5i - 3i = 2i\]
04
Combine Real and Imaginary Parts
Combine the real and imaginary parts simplified from the above steps to form the final result. From Steps 2 and 3, the expression simplifies to:\[8 + 2i\]Thus, the expression \((5-3i)(1+i)\) evaluates to \(8 + 2i\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Distributive Property
In the world of mathematics, the distributive property is a fundamental principle that allows us to simplify expressions and perform calculations with ease. The distributive property states that multiplying a sum by a single term is equivalent to multiplying each addend by the term and then summing the products. To put it simply,
- The principle is used to expand expressions like \(a(b + c) = ab + ac\)
- This same concept helps in dealing with binomials, such as \((5-3i)(1+i)\)
Imaginary Unit
In mathematics, the imaginary unit is usually denoted as \(i\), which stands for the square root of -1. This is a key component in complex numbers, where we express numbers in the form \(a + bi\). Here,
- \(a\) represents the real part
- \(b\) represents the coefficient of the imaginary unit
Simplifying Expressions
Simplifying expressions means reducing them to their simplest form by performing operations and combining like terms. This process involves:
- Identifying and grouping real terms
- Identifying and grouping imaginary terms
- First, focus on the real parts: Combine \(5\) and \(3\) (obtained from \(-3i^2\) where \(i^2 = -1\)), resulting in \(8\).
- Next, handle the imaginary parts: Combine \(5i\) and \(-3i\) to get \(2i\).