Problem 33 - A Graphical Approach to College Algebra

Question

Factor each perfect square trinomial completely. $$16 p^{2}-40 p+25$$

Step-by-Step Solution

Answer

The trinomial factors to \((4p - 5)^2\).

Step 1: Identify the Form

Perfect square trinomials fit the form \(a^2 - 2ab + b^2\) or \(a^2 + 2ab + b^2\). Compare \(16p^2 - 40p + 25\) with these forms.

Step 2: Identify 'a' and 'b' Values

The first term \(16p^2\) is a perfect square, \( (4p)^2 \). The last term \(25\) is a perfect square, \( 5^2 \). Identify \( a = 4p \) and \( b = 5 \).

Step 3: Confirm the Middle Term

Verify that the middle term \(-40p\) can be expressed as \(-2ab\). Calculate \(-2 \times 4p \times 5 = -40p\), which matches the middle term.

Step 4: Factor the Trinomial

Express the trinomial as the square of a binomial using the form \((a - b)^2\). Therefore, \(16p^2 - 40p + 25 = (4p - 5)^2\).

Key Concepts

Factorization

Factorization is a fundamental concept in algebra that involves breaking down an expression into simpler components, or "factors," which when multiplied together give back the original expression. It's like piecing together the basic building blocks to form something more complex. In our example, we deal with a trinomial, which is an algebraic expression composed of three terms. Factorization helps simplify expressions and solve equations with ease.

Specifically, we look for patterns such as the difference of squares, sum of cubes, or, as in our exercise, perfect square trinomials. Recognizing these structures is crucial. They provide shortcuts for writing lengthy expressions in compact, manageable forms, making it simpler to understand and manipulate mathematical equations.

Perfect Square Trinomials

Perfect square trinomials are special forms of algebraic expressions. They are created by squaring a binomial, which is an expression with two terms. Recognizing this form allows us to immediately factor the trinomial with confidence. A perfect square trinomial can be expressed in two standard forms:

• \(a^2 + 2ab + b^2\)
• \(a^2 - 2ab + b^2\)

Identifying a perfect square trinomial greatly simplifies the factorization process. In this exercise:

• First term: \((4p)^2 = 16p^2\)
• Last term: \((5)^2 = 25\)

The middle term should fit as \(-2ab\), and indeed, \(-2 \times 4p \times 5 = -40p\) aligns perfectly with our trinomial.

Understanding this structure confirms the expression's identity as a perfect square trinomial, allowing it to be factorized effortlessly into a square of a binomial.

Binomial Squares

A binomial square is the result of multiplying a binomial by itself. A binomial is a two-term algebraic expression of the form \((a + b)\) or \((a - b)\). When we square these forms, we generate perfect square trinomials explained earlier:

• For \((a + b)^2\), the result is \(a^2 + 2ab + b^2\)
• For \((a - b)^2\), the result is \(a^2 - 2ab + b^2\)

In our example, \((4p - 5)^2\) expands to \(16p^2 - 40p + 25\), demonstrating the binomial square's ability to recreate the original trinomial. Recognizing this reverse process helps not only in solving algebraic problems but also in verifying that our factorization is correct. It is essential knowledge for anyone working to master algebra.