Chapter 1: Problem 63
Factor the polynomial. $$ 25 z^{2}+30 z+9 $$
Short Answer
Expert verified
The polynomial factors as \((5z + 3)^2\).
Step by step solution
01
Identify the Quadratic Expression
The given polynomial is \(25z^2 + 30z + 9\). This is a quadratic expression in the form \(az^2 + bz + c\) where \(a = 25\), \(b = 30\), and \(c = 9\).
02
Check for Perfect Square Trinomial
To verify if the expression is a perfect square trinomial, check if both the first term \(25z^2\) and the last term \(9\) are perfect squares. We find \(\sqrt{25z^2} = 5z\) and \(\sqrt{9} = 3\). Check if twice the product of these roots equals the middle term: \(2 \times 5z \times 3 = 30z\), which matches the middle term.
03
Write the Expression as a Square of a Binomial
Since \(25z^2 + 30z + 9\) is a perfect square trinomial, it can be expressed as the square of a binomial. The expression can be rewritten as \((5z + 3)^2\) because \((5z)^2 = 25z^2\), \(2 \times 5z \times 3 = 30z\), and \(3^2 = 9\).
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Quadratic Expression
A quadratic expression is a polynomial of degree 2, typically written in the form \( ax^2 + bx + c \), where \( a, b, \) and \( c \) are constants, and \( a eq 0 \). In simpler terms, it's an expression with a squared term as its highest power of the variable. Quadratic expressions can show up in various places in math, from physics problems to geometry and economics.
- The coefficient \( a \) is the number in front of the squared term, which in our exercise is 25, making it \( 25z^2 \).
- The coefficient \( b \) is the number in front of the linear term, here 30, making it \( 30z \).
- The constant term \( c \) is the standalone number, which in this case is 9.
Perfect Square Trinomial
A perfect square trinomial is a special type of quadratic expression that can be expressed as the square of a binomial. This means if an expression fits this formula, \( (px + q)^2 = p^2x^2 + 2pqx + q^2 \), then it is a perfect square trinomial.
- The first term \( p^2x^2 \) is formed by squaring the variable term.
- The last term \( q^2 \) is the square of the constant term.
- The middle term \( 2pqx \) equals twice the product of the terms in the binomial.
Binomial Square
A binomial square is what you get when you take a binomial and square it. This is represented as \((px + q)^2\), which expands to \(p^2x^2 + 2pqx + q^2\).
In our task, we transform the quadratic expression \(25z^2 + 30z + 9\) into a binomial square.
In our task, we transform the quadratic expression \(25z^2 + 30z + 9\) into a binomial square.
- We identify \(5z\) as \(p\) and \(3\) as \(q\).
- Thus, \((5z + 3)^2\) becomes the binomial square that matches the original trinomial.
- This transformation simplifies the factorization process, making solving equations or understanding graph relationships much easier.