Lesson 4-2: Properties of equality

Scott started with the equation 5x + 3 = 13. Then he changed the equation to this: 5x + 3 - 7 = 13 - 7. What did he do to change the first equation into the second one?

• He added 7 to the left side.

• He added 7 to both sides.

• He subtracted 7 from both sides.

• He subtracted 7 from the right side.

The addition property of equality states that if the same amount is added to both sides of an equation, then the equation is still true. Which choice shows this by using the starting equation n - 2 = 5

• n - 2 = 5 + 2

• n - 2 + 2 = 5 + 2

• n + 2 - 5

• n - 2 + 5 = 2

Which equation shows the subtraction property of equality by changing the equation a + 2 = 11

• a + 2 - 5 = 11 - 5

• a + 2 + 5 = 11 + 5

• a + 2 ÷ 5 = 11 ÷ 5

• a + 2 = 11

Balanced (or true) equations have the same value on both the left and right sides of the equal sign. Which equations are balanced?

• 3 + 5 = 9

• 3 + 5 = 8

• 3 + 5 = 5 + 3

• 3 + 5 - 2 = 8 - 2

• 3 + 5 - 7 = 3 + 5 + 7

Why is the equation 30 + 27 = 3 not a balanced equation?

• It is a balanced equation. 30 + 27 does equal 3.

• It's not balanced because 30 + 27 is 57, and 57 does not equal 3.

• It's not balanced because 3 + 27 does not equal 30.

• it's not balanced because 30 + 27 is equal to 67, and 67 is 19 times more than 3.

Tell which property was used to change the first equation into the second equation.

n + 6 = 16

(n + 6) ÷ 8 = 16 ÷ 8

• addition property of equality

• subtraction property of equality

• multiplication property of equality

• division property of equality

Tell which property was used to change the first equation into the second equation.

n + 2 = 9

n + 2 - 2 = 9 - 2

• addition property of equality

• subtraction property of equality

• multiplication property of equality

• division property of equality