McGraw Hill Glencoe Algebra 2, 2012
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McGraw Hill Glencoe Algebra 2, 2012 View details
6. Solving Rational Equations and Inequalities
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Exercise 27 Page 577

Start by stating the excluded values. These are the values for which the denominator is 0 in any fraction of the related rational equation.

x<-2 or 2

Practice makes perfect

To solve the given rational inequality, we will follow four steps.

  1. State the excluded values. These are the values for which any of the denominators are 0.
  2. Solve the related rational equation.
  3. Use the values determined in the previous steps to divide a number line into intervals.
  4. Test a value in each interval to determine which intervals contain values that satisfy the inequality.

Let's deal with these steps one at a time.

Excluded Values

Consider the given inequality. x-2/x+2+1/x-2>x-4/x-2Let's find the values for which any of the denominators is 0. c|c x+2=0 & x-2=0 ⇕ & ⇕ x=-2 & x=2 The excluded values for this inequality are 2 and - 2.

Solve the Related Equation

We obtain the related equation by replacing the inequality sign with an equals sign. c|c Inequality & Equation [0.8em] x-2/x+2+1/x-2 > x-4/x-2 & x-2/x+2+1/x-2 = x-4/x-2 Let's solve the equation. First, we will get rid of all of the denominators.

x-2/x+2+1/x-2>x-4/x-2
â–¼
Simplify
(x-2/x+2+1/x-2)* (x+2) (x-2) = x-4/x-2* (x+2) (x-2)
(x-2)(x+2)(x-2)/x+2+(x+2)(x-2)/x-2 = (x-4)(x+2)(x-2)/x-2
(x-2)(x+2)(x-2)/x+2+(x+2)(x-2)/x-2 = (x-4)(x+2)(x-2)/x-2
(x-2)^2+x+2=(x-4)(x+2)

Now that we have an equation without any denominators, we can simplify it as much as possible.

(x-2)^2+x+2=(x-4)(x+2)
â–¼
Simplify
x^2-4x+4+x+2=(x-4)(x+2)
x^2-4x+4+x+2=x(x-4)+2(x-4)
x^2-4x+4+x+2=x^2-4x+2x-8
x^2-3x+6=x^2-2x-8
-3x+6=-2x-8
- x+6=- 8
- x=- 14
x=14

Divide the Number Line Into Intervals

We will divide the number line considering the excluded values x=-2, x=2, and the solution to the related equation x=14.

Test Values

We will now test a value from each interval. Let's start with the interval x<- 2. We will test the point x=- 3. If substituting this point into the original inequality produces a true statement, then the numbers in this interval are solutions. If not, these numbers are not solutions.

x-2/x+2+1/x-2>x-4/x-2
-3-2/-3+2+1/-3-2 ? > -3-4/-3-2
â–¼
Simplify left-hand side
-5/-1+1/-5 ? > -7/-5
-5/-1-1/5 ? > -7/-5
5/1-1/5 ? > 7/5
25/5-1/5 ? > 7/5
24/5? > 7/5
24>7 ✓

Since we obtained a true statement, we can conclude that the numbers less than - 2 are solutions to the inequality. Using the same process, we can determine whether the numbers that belong to the other intervals are solutions.

Interval Test Value Statement
x< - 2 x=- 3 24>5 ✓
- 2< x < 2 x=0 -3>4 *
2 x=5 46>27 ✓
x>14 x=15 107>108 *

We found that the solutions to the given inequality are all the numbers below - 2 or all the numbers between 2 and 14. Solution x<-2 or 2