Select the two properties that justify equating the expressions.

[tex]\[
\begin{array}{l}
10 \cdot (9 + 2 \cdot x) \\
= 10 \cdot 9 + 10 \cdot 2x \\
= 20x + 90
\end{array}
\][/tex]

A. Associative Property of Addition
B. Associative Property of Multiplication
C. Commutative Property of Addition
D. Commutative Property of Multiplication
E. Distributive Property



Answer :

Of course! Let's carefully break down the steps to identify the properties used in the given expressions:

Given expressions:
[tex]\[ 10 \cdot(9 + 2 \cdot x) = 10 \cdot 9 + 10 \cdot 2 \cdot x = 20x + 90 \][/tex]

1. Step 1: Applying the Distributive Property

The first part of the expression involves the distributive property, which states that:
[tex]\[ a \cdot (b + c) = a \cdot b + a \cdot c \][/tex]

Here, the expression:
[tex]\[ 10 \cdot (9 + 2 \cdot x) \][/tex]

can be expanded using the distributive property:
[tex]\[ 10 \cdot 9 + 10 \cdot 2 \cdot x \][/tex]

2. Step 2: Simplifying the Terms

Now we simplify the terms:
[tex]\[ 10 \cdot 9 = 90 \][/tex]
[tex]\[ 10 \cdot 2 \cdot x = 20x \][/tex]

So we have:
[tex]\[ 90 + 20x \][/tex]

3. Step 3: Utilizing the Commutative Property of Addition

Finally, the expression can be rearranged using the commutative property of addition, which states that:
[tex]\[ a + b = b + a \][/tex]

Therefore:
[tex]\[ 90 + 20x \][/tex]

is equivalent to:
[tex]\[ 20x + 90 \][/tex]

Conclusion:

The two properties that justify equating the expressions are:

1. Distributive Property
2. Commutative Property of Addition

These properties explain how the initial expression is expanded and rearranged to reach the final form.