Pearson Algebra 1 Common Core, 2011
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Pearson Algebra 1 Common Core, 2011 View details
5. Solving Rational Equations
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Exercise 25 Page 695

Multiply the numerator on the left-hand side by the denominator on the right-hand side, and the denominator on the left-hand side by the numerator on the right-hand side.

x=3

Practice makes perfect

We will solve the given equation and then check the solutions. 5/x+1=x+2/x+1 Since both fractions are undefined when x=-1, we can suspect that x=-1 is a possible extraneous solution. Let's solve the given equation!

Solving the Equation

We will solve the rational equation by using the Cross Products Property. If a numerator or denominator contains addition or subtraction, be sure to treat each one as a parenthetical factor in the cross multiplication process.

5/x+1=x+2/x+1
5(x+1)=(x+1)(x+2)
5x+5=(x+1)(x+2)
5x+5=x(x+2)+1(x+2)
â–¼
Distribute x & 1
5x+5=x^2+2x+1(x+2)
5x+5=x^2+2x+x+2
â–¼
Simplify
5x+5=x^2+3x+2
5=x^2-2x+2
0=x^2-2x-3
x^2-2x-3=0

We obtained a quadratic equation. Let's identify the values of a, b, and c. x^2-2x-3=0 ⇕ 1x^2+( - 2)x+( - 3)=0 We see that a = 1, b = - 2, and c = - 3. Next, we will substitute these values into the Quadratic Formula.

x=- b±sqrt(b^2-4ac)/2a
x=- ( - 2)±sqrt(( - 2)^2-4( 1)( - 3))/2( 1)
â–¼
Solve using the quadratic formula
x=2±sqrt((- 2)^2-4(1)(- 3))/2(1)
x=2±sqrt(4-4(1)(- 3))/2(1)
x=2±sqrt(4-4(- 3))/2
x=2±sqrt(4+12)/2
x=2±sqrt(16)/2
x=2± 4/2

We will find the values for x by using the positive and the negative signs.

x=2± 4/2
x=2+ 4/2 x=2- 4/2
x=6/2 x=- 2/2
x=3 x=- 1

We found that x=3 and x=- 1 are possible solutions. Now we have to check them!

Checking the Solutions

We check our solutions to see whether any of them are extraneous. To do so, we will substitute x=3 and x=- 1 into the given equation. Let's start with x=3.

5/x+1=x+2/x+1
5/3+1? =3+2/3+1
5/4=5/4 ✓

Since we obtained a true statement, x=- 1 is a solution of the equation. Let's now substitute x=- 1 into the equation.

5/x+1=x+2/x+1
5/-1+1? =-1+2/-1+1
5/0=1/0 *

Note that a fraction with denominator equal to 0 is undefined, so we did not obtain a true statement. Therefore, x=-1 is an extraneous solution.