Addition & Subtraction Properties of Equality

Addition & Subtraction Properties of Equality

​What is an Equation?

​An Equation is a mathematical sentence that uses an equal sign (=) to show that two expressions are equal

Multiple Choice

Which expressions are equal (the same) on both sides of the equals sign?

• 5 x 3 = 15

• 3 + 2 = 9

• 10 - 2 = 15

Multiple Choice

Which expressions are equal (the same) on both sides of the equals sign?

• 5 x 4 = 9

• 17 + 5 = 22

• 18 - 9 = 1

Multiple Choice

When is an equation true?

• When both sides have different numbers

• They are always false

• When both sides are the same

​What is a Variable?

​- A variable is an unknown value

​

​- A solution of an equation is a value for the variable that makes the equation true

Tell which value of the variable is the solution of the equation

​d + 9 = 16 d = 5 , 7 , 9 , 11

​

​Use substitution and replace d with the given options

​

​If d = 5, 5 + 9 = 16 ----> 14 = 16

as we can see there is no balance and it is not equal on both sides.

​

​If d = 7, 7 + 9 = 16, ----> 16 = 16

​there is balance and it is equal on both sides, so d = 7

Multiple Choice

Tell which value of the variable is the solution of the equation.

8a = 56

a = 4 , 5 , 6 , 7

• 4

• 5

• 6

• 7

Multiple Choice

Tell which value of the variable is the solution of the equation.

72 $$\div$$  k = 8

k = 7 , 8 , 9, 10

• 7

• 8

• 9

• 10

​Properties of Equality (POE)

​The property of Equality states that when you perform the same operation on both sides of the equal sign the two sides stay equal

​Properties of Equality (POE)

Multiple Choice

What property of equality is shown below?

25 + d = 36

25 + d - 25 = 36 - 25

• addition property of equality

• subtraction property of equality

• division property of equality

• multiplication property of equality

Multiple Choice

What property of equality is shown below?

y - 12 = 30

y -12 + 12 = 30 +12

• addition property of equality

• subtraction property of equality

• multiplication property of equality

• division property of equality

Multiple Choice

What property of equality is shown below?

7n=28

7n $$\div$$  7 = 28  $$\div$$  7

• addition property of equality

• subtraction property of equality

• multiplication property of equality

• division property of equality

​Using POE you can now solve equations to find the unknown variable

Remember!! We want the variable by itself!!​

g - 8 = 25

​ + 8 +8

​g = 33

Multiple Choice

Solve the following equation

x - 4 = 14

• x = 10
• x = -10
• x = 18
• x = -18

​Solve the following equation

x - 4 = 14

+ 4   + 4 ​

​

​x   =  18

Multiple Choice

Solve the following equation 

8 + n = 16

• n=24
• n=6
• n=2
• n=8

Multiple Choice

Solve the following equation

d + 5 = 10

• d = -5
• d = 5
• d = 0
• no solution

Multiple Choice

Solve the following equation

z - 33 = 234

• z = 267

• z = 231

• z = 317

• z = 281

Multiple Choice

Solve the following equation

y + 65 = 182

• y = 107

• y = 117

• y = 247

• y = 123