Chapter 9: Problem 73
Complete the square to make a perfect square trinomial. Then write the result as a binomial squared. (a) \(p^{2}-22 p\) (b) \(y^{2}+5 y\) (c) \(m^{2}+\frac{2}{5} m\)
Short Answer
Expert verified
(a) \((p - 11)^{2}\), (b) \((y + \frac{5}{2})^{2}\), (c) \((m + \frac{1}{5})^{2}\)
Step by step solution
01
Understand the process
To complete the square, we need to transform a quadratic expression into a perfect square trinomial. This involves adding and subtracting the square of half the coefficient of the linear term.
02
Complete the square for part (a)
Given the expression is: \(p^{2} - 22p\). First, take the coefficient of the linear term, which is -22, divide it by 2 to get -11, and then square it to get 121. So, \(p^{2} - 22p + 121 - 121 = (p - 11)^{2} - 121\). The perfect square trinomial is \(p^{2} - 22p + 121 = (p - 11)^{2}\).
03
Complete the square for part (b)
Given the expression is: \(y^{2} + 5y\). First, take the coefficient of the linear term, which is 5, divide it by 2 to get \(\frac{5}{2}\), and then square it to get \(\frac{25}{4}\). So, \(y^{2} + 5y + \frac{25}{4} - \frac{25}{4} = (y + \frac{5}{2})^{2} - \frac{25}{4}\). The perfect square trinomial is \(y^{2} + 5y + \frac{25}{4} = (y + \frac{5}{2})^{2}\).
04
Complete the square for part (c)
Given the expression is: \(m^{2} + \frac{2}{5}m\). First, take the coefficient of the linear term, which is \(\frac{2}{5}\), divide it by 2 to get \(\frac{1}{5}\), and then square it to get \(\frac{1}{25}\). So, \(m^{2} + \frac{2}{5}m + \frac{1}{25} - \frac{1}{25} = (m + \frac{1}{5})^{2} - \frac{1}{25}\). The perfect square trinomial is \(m^{2} + \frac{2}{5}m + \frac{1}{25} = (m + \frac{1}{5})^{2}\).
05
Write the results as binomial squares
Using the results from the previous steps, write each perfect square trinomial as a binomial squared.For (a): \((p - 11)^{2}\)For (b): \((y + \frac{5}{2})^{2}\)For (c): \((m + \frac{1}{5})^{2}\)
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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 the form \(ax^2 + bx + c\), where \(a\), \(b\), and \(c\) are constants, and \(a eq 0\). In the given exercises, we have quadratic expressions with no constant term \(c\). For instance, \(p^2 - 22p\) and \(y^2 + 5y\) are quadratic expressions because they contain a term with \(x^2\) and a linear term with \(x\). Understanding quadratic expressions is crucial because many algebraic methods, such as completing the square, rely on manipulating these expressions to reveal deeper properties.
perfect square trinomials
A perfect square trinomial is a quadratic expression that can be factored into the square of a binomial. This means it looks like \(a^2 + 2ab + b^2 = (a + b)^2\). To transform a quadratic expression into a perfect square trinomial, follow these steps:
- Identify the quadratic expression, for example, \(y^2 + 5y\)
- Take the coefficient of the linear term (\(b\)), which is 5, divide it by 2 to get \(\frac{5}{2}\)
- Square the result to get \(\frac{25}{4}\)
binomial squared
After completing the square and achieving a perfect square trinomial, the next step is writing the expression as a binomial squared. A binomial squared is a quadratic expression written as \((a + b)^2\) or \((a - b)^2\).
- In exercise (a), from \(p^2 - 22p + 121\) we get \((p - 11)^2\).
- In exercise (b), from \(y^2 + 5y + \frac{25}{4}\) we get \((y + \frac{5}{2})^2\).
- In exercise (c), from \(m^2 + \frac{2}{5}m + \frac{1}{25}\) we get \((m + \frac{1}{5})^2\).