To justify each step in the transformation from Line 1 to Line 3, we can use the following properties:
-
Line 1 to Line 2:
- Property: Commutative Property of Addition
- Justification: This property allows us to rearrange the terms inside the parentheses. The expression \( 4 + 9x \) is reordered to \( 9x + 4 \).
-
Line 2 to Line 3:
- Property: Distributive Property
- Justification: This property enables us to multiply each term inside the parentheses by the factor outside, thus transforming \( 2(9x + 4) \) into \( 2 \cdot 9x + 2 \cdot 4 = 18x + 8 \).
In summary:
- From Line 1 to Line 2: Commutative Property of Addition
- From Line 2 to Line 3: Distributive Property