Chapter 4: Problem 61
Factor. \(4 a^{2}-12 a b+9 b^{2}\)
Short Answer
Expert verified
The factorization is \((2a - 3b)^2\).
Step by step solution
01
Identify the Quadratic
The given expression is a quadratic trinomial: \(4a^2 - 12ab + 9b^2\). We can recognize it in the form \(ax^2 + bx + c\) with \(a = 4\), \(b = -12\), and \(c = 9\).
02
Recognize a Perfect Square Trinomial
Notice that the expression resembles a perfect square trinomial of the form \((A - B)^2 = A^2 - 2AB + B^2\). We suspect that this can be factored as a square of a binomial.
03
Rewrite Each Term
Rewrite \(4a^2\) as \((2a)^2\) and \(9b^2\) as \((3b)^2\). We want to check if \(-12ab = -2(2a)(3b)\). If it is, then the expression is indeed a perfect square trinomial.
04
Check the Middle Term
Calculate \(-2(2a)(3b)\), which results in \(-12ab\). The middle term matches exactly with \(-12ab\) from the original expression. This confirms that \(4a^2 - 12ab + 9b^2\) is a perfect square trinomial.
05
Factor the Trinomial
Since the trinomial matches the form \(A^2 - 2AB + B^2\), it factors as \((A - B)^2\), where \(A = 2a\) and \(B = 3b\). Thus, \(4a^2 - 12ab + 9b^2 = (2a - 3b)^2\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Perfect Square Trinomial
A perfect square trinomial is a special type of quadratic polynomial. It has the form \( A^2 - 2AB + B^2 \) or \( A^2 + 2AB + B^2 \). These trinomials are unique because they can be expressed as the square of a binomial.
In the exercise, you had to factor \(4a^2 - 12ab + 9b^2\). Notice that this looks a lot like the pattern of a perfect square trinomial. We compared it to the formula \( (A - B)^2 = A^2 - 2AB + B^2 \). Here, \(A = 2a\) and \(B = 3b\).
Key Points To Identify a Perfect Square Trinomial:
In the exercise, you had to factor \(4a^2 - 12ab + 9b^2\). Notice that this looks a lot like the pattern of a perfect square trinomial. We compared it to the formula \( (A - B)^2 = A^2 - 2AB + B^2 \). Here, \(A = 2a\) and \(B = 3b\).
Key Points To Identify a Perfect Square Trinomial:
- Look for perfect squares in the first and last terms, \(A^2\) and \(B^2\).
- The middle term must be twice the product of the square roots of the first and last terms.
- If all these conditions are satisfied, the trinomial can be factored into \((A \pm B)^2\).
Quadratic Trinomial
A quadratic trinomial is a polynomial composed of three terms. The main feature of these trinomials is that they contain a term squared, a linear term, and a constant or another squared term.
Their standard form is \( ax^2 + bx + c \), where \( a \), \( b \), and \( c \) are coefficients, and \( x \) is the variable. In our exercise, the expression \( 4a^2 - 12ab + 9b^2 \) is a quadratic trinomial.
Essential Features:
Their standard form is \( ax^2 + bx + c \), where \( a \), \( b \), and \( c \) are coefficients, and \( x \) is the variable. In our exercise, the expression \( 4a^2 - 12ab + 9b^2 \) is a quadratic trinomial.
Essential Features:
- The highest power of the variable is squared.
- Contains three terms that build a quadratic expression.
- These can often be turned into product forms through factorization.
Binomial
A binomial is a polynomial with exactly two terms. It has a simple form compared to other polynomials. Binomials can often be squared or multiplied to form trinomials.
In our context here, recognizing a trinomial as a perfect square allows us to express it as the square of a binomial. For example, \( (2a - 3b)^2 \) is a type of binomial expression. Notice how it's derived from splitting each squared term and reconstructing the middle term using them.
Key Properties of Binomials:
In our context here, recognizing a trinomial as a perfect square allows us to express it as the square of a binomial. For example, \( (2a - 3b)^2 \) is a type of binomial expression. Notice how it's derived from splitting each squared term and reconstructing the middle term using them.
Key Properties of Binomials:
- Simpler structure with two terms.
- Commonly used in factorization, such as completing the square.
- A great stepping stone in rewriting complex expressions in simpler forms.
Algebraic Factorization
Algebraic factorization is the process of breaking down a complex expression into simpler, more manageable components. Factorization helps simplify equations and can reveal insights or roots that aren't immediately obvious.
The main idea is to express a polynomial as a product of its factors—simpler polynomials or variables. In our example, you had to factor the trinomial \(4a^2 - 12ab + 9b^2\) into \((2a - 3b)^2\). By recognizing patterns such as a perfect square, you perform algebraic factorization efficiently.
Benefits of Algebraic Factorization:
The main idea is to express a polynomial as a product of its factors—simpler polynomials or variables. In our example, you had to factor the trinomial \(4a^2 - 12ab + 9b^2\) into \((2a - 3b)^2\). By recognizing patterns such as a perfect square, you perform algebraic factorization efficiently.
Benefits of Algebraic Factorization:
- Reduces complexity, making solving or evaluating expressions easier.
- Helps find zeros or roots of polynomial equations.
- Essential for solving quadratic equations and simplifying fractions.