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: 31

Answer

$t = 10$ or $t = 2$

Work Step by Step

We have a quadratic equation in the form of $ax^2 + bx + c$, where $a$, $b$, and $c$ are all real numbers. 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: $-5$ and $-4$ $-10$ and $-2$ It looks like the second combination will work. Let's put the factors together: $(t - 10)(t - 2) = 0$ 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: $t - 10 = 0$ or $t - 2 = 0$ Add to solve: $t = 10$ or $t = 2$ To check our answer, we substitute each of these values into the original equation to see if the two sides equal one another: $(10)^2 - 12(10) + 20 = 0$ Multiply to simplify: $100 - 120 + 20 = 0$ Subtract or add from left to right: $-20 + 20 = 0$ Add once again: $0 = 0$ The two sides of the equation are equal to one another; therefore, this solution is correct. Let's check the other solution: $(2)^2 - 12(2) + 20 = 0$ Multiply to simplify: $4 - 24 + 20 = 0$ Subtract or add from left to right: $-20 + 20 = 0$ Add once again: $0 = 0$ The two sides of the equation are equal to one another; therefore, this solution is correct.
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