3.1 Addition Property of Equality (APE)

The Addition Property of Equality Rule: if a = b, then a + c = b + c Another Version of the Rule: If a=b, then a+(-c)= b+(-c) Which is the same as: If a=b, then a - c =b - c

To solve for “x” x – 8 = 11 Goal: get “ x ” alone on one side of the equation. How: do the opposite of whatever is keeping “ x ” from being all by itself. Why: by doing the opposite operation, the # on the side of the variable cancels out to 0. Rule: whatever you add/subtract to one side of the equation you must add/subtract to the other. x – = x = 19

Example 1: a - 5 = a = 3

Example :2 19 = k = k

Example 3: a = a = 1.7

Example 4: x = __________________ X= -1.6

Example 5:

Example 6:

Example 7 :

Example 8: A number is increased by 36 is 15. Find the number. Let x = the original number. x + 36 = x = -21

Example 9: A number decreased by 83 is 46. Find the number. Let x = the original number. x - 83 = x = 129

Homework: Page 116 (2-40) even How to set up Homework: 1.Name, period, #, Page#, Problems Assigned 2.Write all questions, signify the answer 3. Show all work by adding/subtracting the same amount to both sides of the equal sign 4. Correct it the next day in class with red pen