Solving Subtraction Equations Core Focus on Introductory Algebra Lesson 3.4

Solve each equation. Show all work and check your solution. 1.f + 57 = = x The sum of p and eight is thirty. Write and solve an equation to find the value of p. Warm-Up f = 103 x = 8.7 y = p + 8 = 30 p = 22

Solving Subtraction Equations Solve equations involving subtraction. Lesson 3.4

The Addition Property of Equality For any numbers a, b and c: If a = b, then a + c = b + c

Example 1 Solve each equation. Check your solution. a.y − 3 = 14 Draw a vertical line through the equals sign as a reminder that whatever is done on one side of the line must be done on the other side of the line also. y − 3 = y = 17 Check the answer by  17 − 3 = 14 substituting the solution14 = 14 into the original equation for the variable.

Example 1 Continued… Solve each equation. Check your solution. b.52 = x − 7 Write the equation and draw a vertical line through the equals sign. 52 = x − = x a Check the answer by  52 = 59 − 7 substituting the solution 52 = 52 into the original equationa for the variable.

Example 1 Continued… Solve each equation. Check your solution. c. Write the equation and draw a vertical line through the equals sign. Check the answer by  substituting the solution into the original equation for the variable.

What is the benefit of solving equations using the Properties of Equality rather than the Guess, Check and Revise method? Communication Prompt

Solve each equation. Show all work and check your solution. 1.g − 11 = = x − h − 317 = y minus twenty-three is six. Write and solve an equation to find the value of y. Exit Problems g = 41 x = 11 h = 799 y − 23 = 6 y = 29