Big Ideas Math Algebra 1, 2015
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Big Ideas Math Algebra 1, 2015 View details
4. Solving Absolute Value Equations
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Exercise 34 Page 33

Plot the solutions on a number line.

Example Solution: |x+7.5|=2.5

Practice makes perfect
To write an absolute value equation, we can begin by thinking about the solutions to the equation as points on a number line. We can use the number line to determine the midpoint and the distance from each point to the midpoint. Our equation will take the following form. |x-Midpoint|=Distance to midpoint Let's plot the given solutions on a number line and determine the midpoint.
From the number line, we can see that the midpoint between - 10 and - 5 is - 7.5, and that the distance from both values to the midpoint is 2.5. Now we can rewrite our equation. |x-Midpoint|&= Distance to midpoint |x-( - 7.5)|&= 2.5 ⇔ |x+7.5|=2.5 We can solve the equation we have created to ensure it has the desired solutions.
|x+7.5|=2.5

lc x+7.5 ≥ 0:x+7.5 = 2.5 & (I) x+7.5 < 0:x+7.5 = - 2.5 & (II)

lcx+7.5=2.5 & (I) x+7.5=- 2.5 & (II)

(I), (II): LHS-7.5=RHS-7.5

lx_1=- 5 x_2=- 10
Keep in mind that this is just one possible absolute value equation we could use.