Chapter 5: Problem 88
Perform the indicated operations. $$ (5 k-6)^{2} $$
Short Answer
Expert verified
The expanded form is \(25k^2 - 60k + 36\).
Step by step solution
01
Understand the Operation
We need to expand the expression \((5k - 6)^2\). This means multiplying \((5k - 6)\) by itself.
02
Apply the FOIL Method
Use the FOIL method which stands for First, Outer, Inner, Last. Expand \((5k - 6)(5k - 6)\) as follows:- First: Multiply the first terms: \(5k \times 5k = 25k^2\).- Outer: Multiply the outer terms: \(5k \times (-6) = -30k\).- Inner: Multiply the inner terms: \(-6 \times 5k = -30k\).- Last: Multiply the last terms: \(-6 \times (-6) = 36\).
03
Combine Like Terms
Add all the resulting terms from the FOIL method: \[25k^2 - 30k - 30k + 36\] Combine the like terms \(-30k\) and \(-30k\) to get:\[25k^2 - 60k + 36\].
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
FOIL Method
When expanding expressions like \((5k - 6)^2\), the FOIL method is a handy tool. FOIL is an acronym for First, Outer, Inner, Last. This process helps you expand the expression systematically. First, recognize that \((5k - 6)^2 = (5k - 6)(5k - 6)\). When using the FOIL method:
- First: Multiply the first terms of each binomial. Here, that's \(5k \times 5k = 25k^2\).
- Outer: Then, multiply the outer terms. This involves \(5k \times (-6) = -30k\).
- Inner: Next, multiply the inner terms, which are \(-6 \times 5k = -30k\).
- Last: Finally, multiply the last terms. Here, it is \(-6 \times -6 = 36\).
Combining Like Terms
After applying the FOIL method, the result will include several terms: \(25k^2 - 30k - 30k + 36\). The step to "Combine Like Terms" is all about simplifying your expression further. This means looking for terms that have the same variable part and combining coefficients. In this instance:
- Like Terms: The terms \(-30k - 30k\) both contain the \(k\) variable. Therefore, they can be combined.
- Combining: Add the coefficients of these like terms: \(-30k - 30k = -60k\).
- Result: After combining, the expression simplifies to \(25k^2 - 60k + 36\).
Quadratic Expressions
Quadratic expressions are polynomial expressions where the highest degree term is a square, denoted as \(ax^2\). In our case, the expanded and simplified expression from \((5k - 6)^2\) is \(25k^2 - 60k + 36\), which is a classic quadratic expression.
- Structure: A standard quadratic expression has the form \(ax^2 + bx + c\).
- Components:
- \(a = 25\), which is the coefficient of the quadratic term.
- \(b = -60\), which is the coefficient of the linear term.
- \(c = 36\), which is the constant term.
- Purpose: Quadratic expressions are critical in functions and equations that involve parabolas. They appear frequently in problems involving motion and optimization.