body{margin:0;} noscript{z-index: 10000; position: fixed; display: block; height: 100%; width: 100%; background: #fff;} noscript .fa{font-size: 40px; display:block; color: #daa520;} noscript div{margin-top: 6%; padding-left: 20px; padding-right: 20px; text-align: center;} ! You must have JavaScript enabled to use this site.

Pearson Algebra 2 Common Core, 2011

PA

Pearson Algebra 2 Common Core, 2011 View details

6. Absolute Value Equations and Inequalities

Continue to next subchapter

Exercise 52 Page 46

How many cases do you have after you remove the absolute value?

2

Practice makes perfect

Before we can solve this equation, we need to isolate the absolute value expression using the Properties of Equality.

2/3|3x-6|=4(x-2)

LHS * 3=RHS* 3

2|3x-6|=12(x-2)

.LHS /2.=.RHS /2.

|3x-6|=6(x-2)

Distribute 6

|3x-6|=6x-12

An absolute value measures an expression's distance from a midpoint on a number line. |3x-6|= 6x-12 This equation means that the distance is 6x-12, either in the positive direction or the negative direction. |3x-6|= 6x-12 ⇒ l3x-6= 6x-12 3x-6= - (6x-12) To find the solutions to the absolute value equation, we need to solve both of these cases for x.

|3x-6|=6x-12

lc 3x-6 ≥ 0:3x-6 = (6x-12) & (I) 3x-6 < 0:3x-6 = - (6x-12) & (II)

lc3x-6=6x-12 & (I) 3x-6= -(6x-12) & (II)

(II): Distribute - 1

l3x-6=6x-12 3x-6= -6x+12

(I), (II): LHS+6=RHS+6

l3x=6x-6 3x= -6x+18

(I): LHS-6x=RHS-6x

l- 3x=- 6 3x= -6x+18

(II): LHS+6x=RHS+6x

l-3x= -6 9x=18

(I): .LHS /(-3).=.RHS /(-3).

lx=2 9x=18

(II): .LHS /9.=.RHS /9.

lx=2 x=2

As we see 2 is the solution to both of the equations.

Checking Our Answers

When solving an absolute value equation, it is important to check for extraneous solutions. We can check our answer by substituting it back into the original equation.

2/3|3x-6|=4(x-2)

x= 2

2/3|3( 2)-6|? =4( 2-2)

Multiply

2/3|6-6|? =4(2-2)

Subtract terms

2/3|0|? =4(0)

|0|=0

2/3(0)? =4(0)

Zero Property of Multiplication

0=0

We see that 2 satisfies the original equation.

Subchapter links

Lesson Check p.45

Practice and Problem-Solving Exercises p.46-48

Standardized Test Prep p.48

Mixed Review p.48