<img src="https://d5nxst8fruw4z.cloudfront.net/atrk.gif?account=iA1Pi1a8Dy00ym" style="display:none" height="1" width="1" alt="" />

# Expression Evaluation with Powers and Grouping Symbols

## Evaluate expressions with parentheses and exponents.

%
Progress

MEMORY METER
This indicates how strong in your memory this concept is
Progress
%
Expression Evaluation with Powers and Grouping Symbols

For her best friend's birthday, Jean bought a huge birthday hat. It's too big to actually wear, so her plan is to add a base to it, buy fabric, and cover it with fabric. Jean needs to know how much fabric to buy. Jean's older brother told her that to find the approximate area of the surface of the birthday hat she can use the following formula:

where  is the diameter of the base of the hat and  is the slant height of the hat.

Jean measured her birthday hat and found that the diameter is 15 inches and the slant height is 18 inches. How can Jean use the formula that her brother gave her to find the surface area of the birthday hat so that she can buy the right amount of fabric?

In this concept, you will learn how to evaluate variable expressions involving exponents and parentheses.

### Evaluating Expressions with Powers

An expression is a mathematical phrase that contains numbers and operations. A variable expression is an expression that contains variables.

To evaluate a variable expression means to find the value of the expression for given values of the variables. To evaluate, substitute the given values for the variables in the expression and simplify using the order of operations (PEMDAS).

Remember that the order of operations are:

1. Parentheses: Start by simplifying any part of the expression in parentheses using the order of operations.
2. Exponents: Rewrite any terms that contain exponents without exponents.
3. Multiplication/Division: Do any multiplication and/or division in order from left to right.
4. Addition/Subtraction: Do any addition and/or subtraction in order from left to right.

Here is an example.

Evaluate the expression  if .

First, substitute 4 in for  in the expression.

Next, notice that this expression has multiplication, exponents, subtraction, parentheses, and addition. According to the order of operations, you must start by simplifying the parts of the expression in parentheses. (4) in the first part of the expression is already simplified.  in the second part of the expression still needs to be simplified.

Next, continue to follow the order of operations and evaluate the exponent. Note that only the 4 is squared. Remember that  means  which is 16.

Now, multiply.

Finally, subtract.

### Examples

#### Example 1

Earlier, you were given a problem about Jean and the birthday hat she bought for her friend's birthday. She wants to find the surface area of the hat so she can buy the correct amount of fabric to cover it. She got the following formula from her brother:

where  is the diameter of the base of the hat and  is the slant height of the hat. Jean measured the birthday hat and found that the diameter is 15 inches and the slant height is 18 inches.

To find the surface area, she should first substitute 15 in for  and 18 in for  in the formula.

Next, notice that this expression has multiplication, division, exponents, parentheses, and addition. According to the order of operations, you must start by simplifying the parts of the expression in parentheses that need to be simplified. Start by simplifying the  at the beginning of the expression.

Now, multiply from left to right. You can use your calculator to help.

The answer is that the surface area of the hat (including the base that she added on) is about 600.525 square inches.

With that knowledge, Jean knows exactly how much fabric she needs to buy to help decorate the birthday hat!

#### Example 2

Evaluate  if  is 4.

First, substitute 4 in for  in the expression.

Next, notice that this expression has multiplication, exponents, subtraction, parentheses, and addition. According to the order of operations, you must start by simplifying the parts of the expression in parentheses that need to be simplified. Start by simplifying the  at the end of the expression.

Next, continue to follow the order of operations and evaluate the exponent.

Now, multiply from left to right.

Finally, add and subtract from left to right. You will subtract first since that comes first in the expression.

#### Example 3

Evaluate  for .

First, substitute 2 in for  in the expression.

Next, notice that this expression has multiplication, exponents, subtraction, parentheses, and addition. According to the order of operations, you must start by simplifying the parts of the expression in parentheses that need to be simplified. Start by simplifying the  at the end of the expression.

Next, continue to follow the order of operations and evaluate the exponent.

Now, multiply.

Finally, add and subtract from left to right. You will subtract first since that comes first in the expression.

#### Example 4

Evaluate  for  and .

First, substitute 3 in for  and 4 in for  in the expression.

Next, notice that this expression has division, addition, parentheses, subtraction, and exponents. According to the order of operations, you must start by simplifying the parts of the expression in parentheses that need to be simplified. Start by simplifying the  in the middle of the expression.

Next, continue to follow the order of operations and evaluate the exponent.

Now, divide. Remember that a fraction bar means division so  is the same as .

Finally, add from left to right.

#### Example 5

Evaluate  if  is 5.

First, substitute 5 in for the  in the expression.

Next, notice that this expression has multiplication, exponents, subtraction, parentheses, and addition. According to the order of operations, you must start by simplifying the parts of the expression in parentheses that need to be simplified. Start by simplifying the  at the end of the expression.

Next, continue to follow the order of operations and evaluate the exponent.

Now, multiply.

Finally, add and subtract from left to right. You will subtract first since that comes first in the expression.

### Review

Evaluate the following variable expressions for .

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

Decide whether each of the following statements are true or false.

13. Parentheses are a grouping symbol.

14. Exponents can't be evaluated unless the exponent is equal to 3.

15. If there is multiplication and division in a problem you always do the multiplication first.

To see the Review answers, open this PDF file and look for section 1.10.

### Notes/Highlights Having trouble? Report an issue.

Color Highlighted Text Notes

### Vocabulary Language: English

Evaluate

To evaluate an expression or equation means to perform the included operations, commonly in order to find a specific value.

Exponent

Exponents are used to describe the number of times that a term is multiplied by itself.

Numerical expression

A numerical expression is a group of numbers and operations used to represent a quantity.

Order of Operations

The order of operations specifies the order in which to perform each of multiple operations in an expression or equation. The order of operations is: P - parentheses, E - exponents, M/D - multiplication and division in order from left to right, A/S - addition and subtraction in order from left to right.

Parentheses

Parentheses "(" and ")" are used in algebraic expressions as grouping symbols.

Variable Expression

A variable expression is a mathematical phrase that contains at least one variable or unknown quantity.

1. [1]^ License: CC BY-NC 3.0

### Explore More

Sign in to explore more, including practice questions and solutions for Expression Evaluation with Powers and Grouping Symbols.