Chapter 5: Problem 21
Factor each polynomial. $$ k^{2}-6 k+9 $$
Short Answer
Expert verified
\[ k^{2}-6k+9 = (k-3)^{2} \]
Step by step solution
01
Identify the Polynomial
Analyze the given polynomial: \[ k^{2}-6k+9 \]
02
Recognize the Quadratic Form
Observe that the polynomial is a quadratic expression of the form \[ ax^{2} + bx + c \] Here, \(a=1\), \(b=-6\), and \(c=9\).
03
Find Factors that Multiply to `c` and Sum to `b`
Look for two numbers that multiply to \(9\) (the constant term) and add up to \(-6\) (the coefficient of the linear term). These two numbers are \(-3\) and \(-3\) because \[ (-3) \times (-3) = 9 \] and \[ (-3) + (-3) = -6 \].
04
Rewrite the Quadratic as a Product of Binomials
Express the quadratic polynomial as a product of two binomials: \[ k^{2}-6k+9 = (k-3)(k-3) \]
05
Consolidate the Expression
Recognize that the expression can be written as the square of a binomial: \[ (k-3)^{2} \]
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Expressions
A quadratic expression is a polynomial of degree 2, which means its highest power of the variable is squared. The general form of a quadratic expression is \[ ax^{2} + bx + c \]where:
- \(a\) is the coefficient of the squared term.
- \(b\) is the coefficient of the linear term.
- \(c\) is the constant term.
Polynomial Factoring
Factoring polynomials involves rewriting a polynomial as a product of simpler polynomials. For quadratic polynomials, this typically means expressing them as a product of two binomials. The key steps are:
- Identify the quadratic form: Analyze the given polynomial \[ ax^{2} + bx + c \]
- Find two numbers that multiply to the constant term \(c\) and add up to the linear coefficient \(b\).
- Rewrite the quadratic expression as the product of two binomials.
Binomials
A binomial is a polynomial that has exactly two terms. Binomials can often be factors of quadratic expressions. In the context of our quadratic \[ k^{2} - 6k + 9 \], we identified that it can be expressed as the product of the binomials \( (k-3)(k-3) \). Recognizing binomial patterns is crucial:
- It simplifies the process of factoring quadratics.
- It helps in understanding the product of sums and differences.
- It assists in recognizing perfect square trinomials (like our current example).