Intermediate Algebra: Connecting Concepts through Application

Published by Brooks Cole
ISBN 10: 0-53449-636-9
ISBN 13: 978-0-53449-636-4

Chapter 4 - Quadratic Functions - Chapter Review Exercises - Page 400: 32

Answer

$p = -9$ or $p = 3$

Work Step by Step

First, we want to rewrite this equation as a quadratic one. The quadratic equation is given as: $ax^2 + bx + c$, where $a$, $b$, and $c$ are all real numbers. To do this, we subtract $27$ from each side of the equation: $p^2 + 6p - 27 = 0$ To factor this equation, we want to find which factors, when multiplied, will give us the product of the $a$ and $c$ terms but when added together will give us the $b$ term. Let's look at possible factors: $9$ and $-3$ $27$ and $-1$ It looks like the first combination will work. Let's put the factors together: $(p + 9)(p - 3) = 0$ According to the zero product property, if the product of two factors equals $0$, then either factor can be $0$; therefore, we can set each of these factors equal to $0$ and solve: $p + 9 = 0$ or $p - 3 = 0$ Add or subtract to solve: $p = -9$ or $p = 3$ To check our answer, we substitute each of these values into the original equation to see if the two sides equal one another: $(-9)^2 + 6(-9) = 27$ Multiply to simplify: $81 - 54 = 27$ Subtract: $27 = 27$ The two sides of the equation are equal to one another; therefore, this solution is correct. Let's check the other solution: $(3)^2 + 6(3) = 27$ Multiply to simplify: $9 + 18 = 27$ Subtract: $27 = 27$ The two sides of the equation are equal to one another; therefore, this solution is correct.
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