Properties of Equality

Properties of Equality

How can you keep an equation balanced?

ADDITIONAL PROPERTY OF EQUALITY

How do you know that (5 + 3) + 2 = 8 + 2?

• It allows you to add the same amount to both sides of an equation.

• Add both sides of the equation to make sure they equal (remember PEMDAS, if needed).

• SOLVE: (5 + 3) + 2 = 8 + 2

• SOLVE: 8 + 2 = 8 + 2

• SOLVE: 10 = 8 + 2

• SOLVE: 10 = 10

Does (5 + 3) + 2 = 8 + 2? Why or why not?

Yes, because the same number is added to both sides.

SUBTRACTION PROPERTY OF EQUALITY

How do you know that (5 + 3) - 2 = 8 - 2?

• It allows you to subtract the same amount to both sides of an equation.

• Subtract both sides of the equation to make sure they equal (remember PEMDAS, if needed).

• SOLVE: (5 + 3) - 2 = 8 - 2

• SOLVE: 8 - 2 = 8 - 2

• SOLVE: 6 = 8 - 2

• SOLVE: 6 = 6

Does (5 + 3) - 2 = 8 - 2? Why or why not?

Yes, because the same number is added to both sides.

MULTIPLICATION PROPERTY OF EQUALITY

How do you know that (5 + 3) (2) = 8 (2)?

• It allows you to multiply the same amount to both sides of an equation.

• Multiply both sides of the equation to make sure they equal (remember PEMDAS, if needed).

• SOLVE: (5 + 3) (2) = 8 (2)

• SOLVE: 8 (2) = 8 (2)

• SOLVE: 16 = 8 (2)

• SOLVE: 16 = 16

Does (5 + 3) (2) = 8 (2)? Why or why not?

Yes, because the same number is added to both sides.

DIVISION PROPERTY OF EQUALITY
How do you know that  $\left(5\ +\ 3\right)\div2\ =\ 8\div2$  ?

• It allows you to divide the same amount to both sides of an equation.

• Divide both sides of the equation to make sure they equal (remember PEMDAS, if needed).

• SOLVE:  $(5+3)\div2=8\div2$  

• SOLVE:  $8\div2=8\div2$  

• SOLVE:  $4=8\div2$  

• SOLVE: 4 = 4

Does

 $\left(5+3)\div2=8\div2\right)$  ? Why or why not?

Yes, because the same number is added to both sides.

Now It Is Your Turn!

Remember to look over the set of equations and explain why or why not they equal.

Fill in the Blanks

If, 23 + 37 = 60, does 23 + 37 + 9 = 60 + 9? Why or why not?

Fill in the Blanks

If 7m = 63, does 7m - 9 = 63 - 9? Why or why not?

Fill in the Blanks

 $If\ 35\ -\ 7\ =\ 28,\ does\ \left(35\ -\ 7\right)\div7\ -\ 28\div28?\ Why\ or\ why\ not?$  

Fill in the Blanks

If 10 (3) = 30, does 10 (3) + 4 = 30 + 5? Why or why not?

Fill in the Blanks

 $If\ 102\div2\ =\ 51,\ does\ 102\div2\ \left(3\right)\ =\ 51\ \left(3\right)?\ Why\ or\ why\ not?$  

Poll

How Do You Feel About Adding, Subtracting, Multiplying, and Dividing Properties of Equality?

• Great!

• So-So.

• Confused?