7th Grade Helpful Homework Hints

Today we worked on solving equations containing integers, this in the student Holt textbook chapter 2 section 5. Below you will find examples to assist with these kinds of problems.

Ex.

m + 3 = 15 add the opposite of 3 to both sides
+(- 3) +(-3)
m = 12

Check (substitue the value for the variable)

m + 3 = 15

12 + 3 = 15
15 = 15 (check) both sides equal

{note: when you add opposites they cancel each other out i.e. 3 + (-3) = 0}

Ex.

-2 + r = 6 add the opposite of -2 to both sides
+2 +2
r = 8

Check (substitute the value for the variable)

-2 + r = 6

-2 + 8 = 6
6 = 6 (check) both sides equal


Ex.
x - 7 = 28
+ 7 +7

x = 35

check
x - 7 = 28

35 - 7 = 28

28 = 28

Ex.

13x = 26 divide both sides by the coefficent (number attached to the variable)
13 13

x = 2

Check (substitute the value for the variable)

13x = 26

13(2) = 26

26 = 26 (check) both sides equal


Ex.

x = 15 multiply both sides by the denominator
3

3 (x) = (15) 3
(3)

x = 45

note: By multiplying both the fraction by the denominator the denominator is cancelled

Check (substitue the value for the variable into the equation)

x = 15
3

45 = 15
3

15 = 15 (check) both sides equal