Pre-Algebra : Operations and Properties

Study concepts, example questions & explanations for Pre-Algebra

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Example Questions

Example Question #121 : Operations

Solve the equation below:

\(\displaystyle 8 + 4 * 6 - 12 =\)

Possible Answers:

\(\displaystyle 16\)

\(\displaystyle 6\)

\(\displaystyle 60\)

\(\displaystyle 0\)

\(\displaystyle 20\)

Correct answer:

\(\displaystyle 20\)

Explanation:

When solving an order of operations question use the GEMDAS method.

G = Grouping Symbols

E = Exponets

M/D = Multiplication OR Division from left to right.

A/S = Addition OR Subtraction from left to right.

\(\displaystyle 8 + 4 * 6 - 12 =\)

\(\displaystyle 4 * 6 = 24\)

\(\displaystyle 8 + 24 - 12 =\)

\(\displaystyle 32 - 12 =\) \(\displaystyle 20\)

Example Question #122 : Operations

Solve using the order of operations:

\(\displaystyle 9 \cdot 3^2 + 12 \div 3\)

Possible Answers:

\(\displaystyle 76\)

\(\displaystyle 22\)

\(\displaystyle 58\)

\(\displaystyle 85\)

\(\displaystyle 31\)

Correct answer:

\(\displaystyle 85\)

Explanation:

The order of operations is the order in which you must solve a problem.  The order is defined as

PARENTHESES

EXPONENTS

MULTIPLICATION

DIVISION

ADDITION

SUBTRACTION

where we solve parentheses first, followed by exponents, and so on.  Following the order of operations, we get

\(\displaystyle 9 \cdot 3^2 + 12 \div 3\)

\(\displaystyle 9 \cdot 9 + 12 \div 3\)

\(\displaystyle 81 + 12 \div 3\)

\(\displaystyle 81 + 4\)

\(\displaystyle 85\)

Example Question #121 : Order Of Operations

Solve using the order of operations:

\(\displaystyle 4(3^2 + 5^2) - 24 \div 2\)

Possible Answers:

\(\displaystyle 20\)

\(\displaystyle 124\)

\(\displaystyle 148\)

\(\displaystyle 56\)

\(\displaystyle 50\)

Correct answer:

\(\displaystyle 124\)

Explanation:

The order of operations is a specific order in which you must solve a problem.  It is defined as

PARENTHESES

EXPONENTS

MULTIPLICATION

DIVISION

ADDITION

SUBTRACTION

where you solve parentheses first, followed by exponents, and so on.  

So, following this order, we get

\(\displaystyle 4(3^2 + 5^2) - 24 \div 2\)

PARENTHESES

\(\displaystyle 4(9 + 25) - 24 \div 2\)

\(\displaystyle 4(34) - 24 \div 2\)

MULTIPLICATION

\(\displaystyle 136-24 \div 2\)

DIVISION

\(\displaystyle 136 - 12\)

SUBTRACTION

\(\displaystyle 124\)

Example Question #121 : Operations And Properties

What is the solution to the following problem?

\(\displaystyle 2(4-3)^{2}+14\) 

Possible Answers:

\(\displaystyle 18\)

\(\displaystyle 40\)

\(\displaystyle 21\)

\(\displaystyle 16\)

\(\displaystyle 28\)

Correct answer:

\(\displaystyle 16\)

Explanation:

This problem requires proper order of operations. Remember the acronym for the order of operations: PEMDAS. This acronym will help you to remember the proper order for solving problems:

  1. Parentheses
  2. Exponents
  3. Multiplication and Division (whichever comes first as you read the problem from left to right)
  4. Addition and Subtraction (whichever comes first as you read the problem from left to right)

Step 1: Parentheses

\(\displaystyle 2(4-3)^{2}+14\)

\(\displaystyle 2(1)^{2}+14\)

Step 2: Exponents

\(\displaystyle 2(1)^{2}+14=2(1\cdot 1)+14=2(1)+14\)

Step 3: Multiplication

\(\displaystyle 2(1)+14=2+14\)

Step 4: Addition

\(\displaystyle 2+14=16\)

Example Question #125 : Operations

Fifty friends are renting a restaurant venue for a graduation party. Rental of the venue requires a \(\displaystyle \$315.00\) up-front deposit plus a \(\displaystyle \$25.00\) per hour operation cost. The friends have booked the venue from \(\displaystyle 8:00$ AM\) to \(\displaystyle 5:00 $ PM\). If the friends have agreed to split the cost evenly, how much money should each person expect to pay? 

Possible Answers:

\(\displaystyle \$6.80\)

\(\displaystyle \$31.30\)

\(\displaystyle \$10.80\)

\(\displaystyle \$6.30\)

\(\displaystyle \$9.80\)

Correct answer:

\(\displaystyle \$10.80\)

Explanation:

First, let's write an equation that will calculate the cost for each person.

\(\displaystyle \textup{Cost}=\frac{\$315+(\$25\times h\textup{ hours})}{50 \textup{ students}}\)

We need to calculate the number of hours that the students plan to rent the venue from \(\displaystyle 8:00$ AM\) to \(\displaystyle 5:00 $ PM\).

\(\displaystyle \textup{8:00 AM to 12:00 PM=4 hours}\)

\(\displaystyle \textup{12:00 PM to 5:00 PM=5 hours}\)

Let's add these values together to calculate our x-variable (i.e. the number of hours that the students will rent the venue).

\(\displaystyle 4+5=9\textup{ hours}\)

Now, we can substitute in the number of hours that the students will rent the venue and calculate the cost that each student should expect to pay.

\(\displaystyle \textup{Cost}=\frac{\$315+(\$25\times 9\textup{ hours})}{50 \textup{ students}}\)

\(\displaystyle \textup{Cost}=\frac{\$315+\$225}{50 \textup{ students}}\)

\(\displaystyle \textup{Cost}=\frac{\$540}{50 \textup{ students}}\)

Last, we need to divide this total cost by the number of students. 

\(\displaystyle \textup{Cost}=\$10.80\)

Example Question #123 : Order Of Operations

Fahrenheit temperature can be converted to its Celsius equivalent using the following formula:

\(\displaystyle ^{\circ}\textup{C} = (^{\circ}\textup{F}-32)\times\frac{5}{9}\).

Similarly, Celsius temperature can be converted to its Fahrenheit equivalent using another formula:

\(\displaystyle ^{\circ}\textup{F} = \frac{9}{5} ^{\circ}\textup{C} + 32\).

A scientist knows that nickel melts at the following temperature:

\(\displaystyle \textup{1,455} ^{\circ } \textup{C}\)

In order to complete an experiment, the scientist needs to know this temperature in degrees Fahrenheit. What is the melting point of nickel in degrees Fahrenheit?

Possible Answers:

None of these

\(\displaystyle 2\textup,651^\circ $F\)

\(\displaystyle 776^\circ $F\)

\(\displaystyle 1\textup,524^\circ $F\)

\(\displaystyle 791^\circ $F\)

Correct answer:

\(\displaystyle 2\textup,651^\circ $F\)

Explanation:

Since we are converting from Celsius to Fahrenheit, we need to use the following formula:

 \(\displaystyle ^{\circ}\textup{F} = \frac{9}{5} ^{\circ}\textup{C} + 32\).

Substitute the value for the melting point of nickel in degrees Celsius and solve. 

\(\displaystyle ^{\circ}\textup{F} = \frac{9}{5} \cdot \textup{1,455} ^{\circ } \textup{C} + 32\)

According to the order of operations, we need to perform the multiplication/division operations first.

\(\displaystyle ^{\circ}\textup{F} = \frac{9\times\textup{1,455} ^{\circ } \textup{C}}{5}+32\)

\(\displaystyle ^{\circ}\textup{F} = \frac{\textup{13,095}}{5}+32\)

Simplify.

\(\displaystyle ^{\circ}\textup{F} =\textup{2,619}+32\)

Solve.

\(\displaystyle ^{\circ}\textup{F} = \textup{2,651}\)

Example Question #127 : Operations

Select the equation that reflects the phrase below. 

First subtract \(\displaystyle 28\) and \(\displaystyle 17\), then divide by \(\displaystyle 3\).

Possible Answers:

\(\displaystyle (28-17)\div3\)

\(\displaystyle 28\div17-3\)

\(\displaystyle 28-17\div3\)

\(\displaystyle 28\div3-17\)

\(\displaystyle 28-(7\div3)\)

Correct answer:

\(\displaystyle (28-17)\div3\)

Explanation:

Because we want to subtract 28 and 17 first, we need to set that off into parentheses due to the order of operation rules. Remember: without parentheses, division would come before subtraction.  The parentheses around (28 - 17) tells you that the subtraction comes first, then we can do the division by 3.

Example Question #91 : Operations & Algebraic Thinking

Select the equation that reflects the phrase below. 

First add \(\displaystyle 8\) and \(\displaystyle 9\), then multiply by \(\displaystyle 2\)

Possible Answers:

\(\displaystyle 8+9\times2\)

\(\displaystyle 2\times9+8\)

\(\displaystyle (18+9)\times2\)

\(\displaystyle (8+9)\times2\)

\(\displaystyle 2\times8+9\)

Correct answer:

\(\displaystyle (8+9)\times2\)

Explanation:

Because we want to add \(\displaystyle 8\) and \(\displaystyle 9\) first, we need to set that off into parentheses due to the order of operation rules. Then we can multiply by \(\displaystyle 2\)

Example Question #122 : Operations And Properties

Simplify the expression.

\(\displaystyle 6x+7y-3x+2y\)

Possible Answers:

\(\displaystyle 9y-3x\)

\(\displaystyle 5y-3x\)

\(\displaystyle 3x+9y\)

\(\displaystyle 6x-4y\)

\(\displaystyle 9xy-6xy\)

Correct answer:

\(\displaystyle 3x+9y\)

Explanation:

\(\displaystyle 6x+7y-3x+2y\)

Re-write the expression to group like terms together.

\(\displaystyle (6x-3x)+(7y+2y)\)

Simplify.

\(\displaystyle 3x+9y\)

Example Question #123 : Operations And Properties

What is \(\displaystyle 2x^{2}+3x^{2}\)  simplified?

Possible Answers:

\(\displaystyle 5x^{4}\)

\(\displaystyle 5x^{2}\)

\(\displaystyle 6x^{4}\)

\(\displaystyle 6x^{2}\)

Correct answer:

\(\displaystyle 5x^{2}\)

Explanation:

To simplify a problem like the example above we must combine the like-termed variables.

Like terms are the terms that share the same variable(s) to the same power. In this example the like term is \(\displaystyle x^{2}\).

To combine like terms the variable \(\displaystyle x^{2}\) stays the same and you add the numbers in front.

Perform the necessary addition, \(\displaystyle 2+3=5\), to get \(\displaystyle 5x^{2}\).

We have the simplified version of the equation, \(\displaystyle 5x^{2}\).

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