Chapter 8: Problem 57
Add the proper constant to each binomial so that the resulting trinomial is a perfect square trinomial. See Section 8.1. $$ z^{2}-16 z $$
Short Answer
Expert verified
Add 64 to form the perfect square trinomial \((z - 8)^2 = z^2 - 16z + 64\).
Step by step solution
01
Understanding the Problem
To make the given binomial a perfect square trinomial, we need to transform it into the form \((z-a)^2\), which expands to \(z^2 - 2az + a^2\). Therefore, we need to find a constant \(a^2\) to complete the square of the binomial \(z^2 - 16z\).
02
Determining the Linear Term
For the binomial \(z^2 - 16z\), the Linear term "\(-2a\)" is given as \(-16z\), hence \(-2a = -16\). By solving \(-2a = -16\), we find \(a\).
03
Solving for a
We solve the equation \(-2a = -16\). Dividing both sides by \(-2\), we get \(a = 8\).
04
Finding the Constant Term
Once \(a\) is known to be 8, we calculate the perfect square constant by evaluating \(a^2\). Thus, the constant to add is \(8^2 = 64\).
05
Verification by Expansion
To verify, we check that \((z - 8)^2\) expands to the form we started with plus the constant. Expanding \((z - 8)^2\) yields \(z^2 - 16z + 64\), confirming the correctness of adding 64.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Binomial
A binomial is a type of polynomial that consists of exactly two terms. In the context of algebra, these two terms can be represented generally as follows: a
- leading term, often including a variable with an exponent
- and a secondary term, which can be a constant or another term with the same variable but a different coefficient and exponent.
- \( z^2 \) is the leading term
- and \(-16z\) is the secondary term.
Completing the Square
Completing the square is a systematic method used to transform a quadratic expression, particularly a binomial, into a perfect square trinomial. This is useful in many algebraic operations, including solving quadratic equations and analyzing quadratic functions.To complete the square for a binomial such as \( z^2 - 16z \), follow these steps:
- Identify the coefficient of the linear term, here it is -16, which equates to \(-2a\) if the expression were to be set as a trinomial in the form \((z-a)^2\).
- Solve for "a" by the equation \(-2a = -16\), obtaining the value, which in this case is 8.
- Square that value to find the constant term needed to complete the binomial into a perfect square trinomial, so \(8^2 = 64\).
Quadratic Expressions
Quadratic expressions describe a polynomial where the highest degree of any term is two. The standard form looks like \(ax^2 + bx + c\), where "a", "b", and "c" are constants, and "x" is a variable. Most importantly, these equations form parabolas when graphed.In practical terms, a quadratic expression might emerge in various forms that need manipulation, often requiring methods like completing the square to simplify analysis and solutions. In the exercise, the quadratic expression \(z^2 - 16z\) needed transforming into a format that reveals more about its properties. By completing the square and adding 64, the expression becomes \( (z - 8)^2 \). This form:
- reveals the vertex of the parabola, occurring at \( z = 8 \)
- and provides an insight into how the graph positions and stretches.