Adding and Subtracting Equations

Question 1

Equation – a mathematical sentence that contains an _________ sign. The equation acts like a balance scale.

Answer 1

Equal

Question 2

In order to solve an equation, we will use the strategy of inverse operation. Inverse operation is the ____________ operation and it helps us to isolate the variable (get the variable alone).

Answer 2

Opposite

Question 3

The inverse of addition is ____________ because it will undo addition.

The inverse of subtraction is ____________ because it will undo subtraction.

Remember our additive inverse property? Any number plus its opposite will always equal ________.

Examples:
4 + -4 = ____ -8 + 8 = ____

Answer 3

The inverse of addition is subtraction because it will undo addition.

The inverse of subtraction is addition because it will undo subtraction.

Remember our additive inverse property? Any number plus its opposite will always equal zero.

Examples:
4 + -4 = 0 -8 + 8 = 0

Question 4

Steps:

1.) Find the inverse operation of the number on the ________ side of the equation as the variable.

2.) Add or subtract on ________ sides of the equation to isolate the variable.

3.) Check your answer by substituting your solution in the original equation to see if it makes the equation ________.

Answer 4

Steps:

1.) Find the inverse operation of the number on the same side of the equation as the variable.

2.) Add or subtract on both sides of the equation to isolate the variable.

3.) Check your answer by substituting your solution in the original equation to see if it makes the equation true.

Question 5

Now try these steps! Do the checks!!!

1.) s + 19 = 47

Answer 5

Now try these 3 steps! Do the checks!!!

1.) s + 19 = 47
-19 = -19
47 = 47

Question 6

2.) 112 = x – 74

Answer 6

2.) 112 = x – 74
112 = x - 74
112 = 186 - 74
112 = 112

Question 7

3.) Some brown eggs and 8 white eggs make a dozen. How many brown eggs are there?

Write an equation, solve, and check.

Answer 7

b + 8 = 12
-8 = -8
b =4

CHECK:
b + 8 = 12
4 + 8 = 12