1. Section 2.5
Solving Linear Equations in One Variable Using the Multiplication-Division Principle

2. 2.5 Lecture Guide: Solving Linear Equations in One Variable Using the Multiplication-Division Principle
Objective: Solve linear equations in one variable using the multiplication-division principle.
Just as the addition-subtraction principle allows us to strategically add or subtract the same value on both sides of an equation, the multiplication-division principle allows us to strategically multiply or divide values on both sides of an equation to give the desired coefficient on the variable.

3. 1. Give a verbal description of the correct step to solve each equation below, and then solve the equation:
(a)
(b)
(c)
(d)

4. Multiplication-Division Principle of Equality
Verbally
If both sides of an equation are multiplied or divided by the same nonzero number, the result is an equivalent equation.
Algebraically
Numerical Example
If a, b, and c are real numbers and
is equivalent to
, then
is equivalent to
and to ; .
and
is equivalent to .

5. Strategy for Solving Linear Equations
Step 1: Simplify each side of the equation.
(a) If the equation contains fractions, simplify by multiplying both sides of the equation by the least common denominator (LCD) of all the fractions.
(b) If the equation contains grouping symbols, simplify by using the distributive property to remove the grouping symbols and then combine like terms.
Step 2: Using the addition-subtraction principle of equality, isolate the variable terms on one side of the equation and the constant terms on the other side.
Step 3: Using the multiplication-division principle of equality, solve the equation produced in Step 2.

6. The following examples require using the multiplication-division principle of equality. Some will also require using the addition-subtraction principle of equality. Solve each equation. Note that we can check our solutions of each equation. 2.

7. The following examples require using the multiplication-division principle of equality. Some will also require using the addition-subtraction principle of equality. Solve each equation. Note that we can check our solutions of each equation. 3.

8. The following examples require using the multiplication-division principle of equality. Some will also require using the addition-subtraction principle of equality. Solve each equation. Note that we can check our solutions of each equation. 4.

9. The following examples require using the multiplication-division principle of equality. Some will also require using the addition-subtraction principle of equality. Solve each equation. Note that we can check our solutions of each equation. 5.

10. The following examples require using the multiplication-division principle of equality. Some will also require using the addition-subtraction principle of equality. Solve each equation. Note that we can check our solutions of each equation. 6.

11. The following examples require using the multiplication-division principle of equality. Some will also require using the addition-subtraction principle of equality. Solve each equation. Note that we can check our solutions of each equation. 7.

12. The following examples require using the multiplication-division principle of equality. Some will also require using the addition-subtraction principle of equality. Solve each equation. Note that we can check our solutions of each equation. 8.

13. The following examples require using the multiplication-division principle of equality. Some will also require using the addition-subtraction principle of equality. Solve each equation. Note that we can check our solutions of each equation. 9.

14. The following examples require using the multiplication-division principle of equality. Some will also require using the addition-subtraction principle of equality. Solve each equation. Note that we can check our solutions of each equation.
10.

15. The following examples require using the multiplication-division principle of equality. Some will also require using the addition-subtraction principle of equality. Solve each equation. Note that we can check our solutions of each equation.
11.

16. The following examples require using the multiplication-division principle of equality. Some will also require using the addition-subtraction principle of equality. Solve each equation. Note that we can check our solutions of each equation.
12.

17. The following examples require using the multiplication-division principle of equality. Some will also require using the addition-subtraction principle of equality. Solve each equation. Note that we can check our solutions of each equation.
13.

18. 14. Note the difference between simplifying expressions and solving equations:
(a) Simplify
(b) Solve

19. Mentally estimate the solution of each equation and then use your calculator to solve the equation.
15.
Mental estimate: _________ Calculator solution: _________

20. Mentally estimate the solution of each equation and then use your calculator to solve the equation.
16.
Mental estimate: _________ Calculator solution: _________

21. 17. Write an algebraic equation for the following statement and then solve the equation.
Verbal Statement: Three times the quantity x plus four is two less than x.
Algebraic Equation:
Solve this equation:

22. 18. The perimeter of the rectangle shown equals . Find a.

23. 19. Solve the equation
by letting
equal the left side of the equation and
equal the
right side of the equation.
(a) Create a table on your calculator with the table settings: TblStart = 0;
Complete the table below. x Y1 Y2 1 2 3 4 5 6
The x-value at which the two y-values are equal is ______.

24. 19. Solve the equation
by letting
equal the left side of the equation and
equal the
right side of the equation.
(b) Use your calculator to create a graph of
and
using a viewing window of
. Use the
Intersect feature to find the point where these two lines intersect. Draw a rough sketch below. The values in the table will help.
The point where the two lines intersect has an x-coordinate of ______.

25. 19. Solve the equation
by letting
equal the left side of the equation and
equal the
right side of the equation.
(c) Solve the equation
algebraically.
(d) Check your solution.