Simplifying and Evaluating Expressions Using the Distributive Property

Learning Outcomes

• Simplify an algebraic expression using the distributive property
• Evaluate an algebraic expression for a given value using the distributive property

Using the Distributive Property With the Order of Operations

Sometimes we need to use the Distributive Property as part of the order of operations. Start by looking at the parentheses. If the expression inside the parentheses cannot be simplified, the next step would be multiply using the distributive property, which removes the parentheses. The next two examples will illustrate this.

example

Simplify: $8 - 2\left(x+3\right)$

Solution:

 $8-2(x+3)$ Distribute. $8-2\cdot x-2\cdot 3$ Multiply. $8-2x-6$ Combine like terms. $-2x+2$

example

Simplify: $4\left(x - 8\right)-\left(x+3\right)$

try it

In the following example, we simplify more expressions that require the distributive property.

Evaluate Expressions Using the Distributive Property

Some students need to be convinced that the Distributive Property always works.

In the examples below, we will practice evaluating some of the expressions from previous examples; in part 1, we will evaluate the form with parentheses, and in part 2 we will evaluate the form we got after distributing. If we evaluate both expressions correctly, this will show that they are indeed equal.

example

When $y=10$ evaluate:
1. $6\left(5y+1\right)$
2. $6\cdot 5y+6\cdot 1$

example

When $y=3$, evaluate
1. $-2\left(4y+1\right)$
2. $-2\cdot 4y+\left(-2\right)\cdot 1$

example

When $y=35$ evaluate
1. $-\left(y+5\right)$

2. $-y-5$ to show that $-\left(y+5\right)=-y-5$

try it

The following video provides another way to show that the distributive property works.