Big Ideas Math Integrated I, 2016
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Big Ideas Math Integrated I, 2016 View details
Chapter Review
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Exercise 15 Page 266

Consider that an absolute value equation in the form |ax+b|=|cx+d| has two related equations.

x=-5

Practice makes perfect
An absolute value equation in the form |ax+b|=|cx+d| has two related equations. Equation1: ax+b&= cx+d Equation2: ax+b&=-(cx+d) In this case, we are given the equation |x+1|=|- x-9|. Let's split it into the two cases. Equation1: x+1&= - x-9 Equation2: x+1&=-(- x-9)

Now, let's solve each equation separately.

First Equation

To graph the equation x+1=- x-9, we will create two functions out of the left- and right-hand sides of the equation. y=x+1 and y=- x -9 The x-coordinate where the graphs of these equations intersect is the solution to our equation.

intersection equation 1
The graphs intersect at x=-5, which is our solution. Let's check whether it is correct by substituting it into the original equation.
|x+1|=|- x-9|
| -5+1|? =|-( -5)-9|
â–Ľ
Simplify
|-5+1|? =|5-9|
|- 4|? =|- 4|
4=4 âś“
Since the resulting statement is true, our solution is correct.

Second Equation

Again, to graph the equation x+1=-(- x-9), we will create two functions out of the left- and right-hand sides of the equation.

x+1=- (- x-9)
First Function y=x+1
Second Function y=- (- x-9) ⇔ y=x+9

Once more, the x-coordinate where the graphs of these functions intersect is the solution to our equation.

parallel lines

We have found that these lines are parallel, so they will never intersect. Therefore, there is no solution to this equation.

Conclusion

By checking the two related equations of the absolute value equation, we found that the only solution is x=-5.