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| 16 Theory slides |
| 11 Exercises - Grade E - A |
| Each lesson is meant to take 1-2 classroom sessions |
Here are a few recommended readings before getting started with this lesson.
Tearrik is really excited about a game that is coming out this weekend. He decides to sell some of his stuff so that he can make enough money to buy the game.
When dealing with variables, sometimes other numbers are needed to complete a mathematical idea. One type of these numbers is coefficients.
Another type of numbers that appear with variables is called constants.
The applet below displays different variables multiplied by coefficients. Answer the indicated question correctly.
An algebraic expression is a valid combination of numbers, variables, and mathematical operations. For example, in the expression 2x+3, the variable x is being multiplied by its coefficient 2, and this product is then added to the constant 3.
Algebraic expressions are made by adding or subtracting smaller expressions called terms.
+or
−signs.
Mathematical Expression | Number of Terms | Terms |
---|---|---|
7x | 1 | 7x |
8 | 1 | 8 |
8x−2(5) | 2 | 8x and -2(5) |
x2+y2+4 | 3 | x2, y2, and 4 |
2x2−5x−122 | 3 | 2x2, -5x, and -122 |
At his garage sale, Tearrik is selling some of his old shirts and pants.
Remember that an algebraic expression is a combination of numbers, variables, and mathematical operations.
An algebraic expression is a combination of numbers, variables, and mathematical operations. The terms are separated by +
or −
signs. In verbal expressions, some words or phrases may imply certain math operations.
Key Words and Phrases | |
---|---|
Addition | added to, plus, sum of, more than, increased by, total of and |
Subtraction | subtracted from, minus, difference of, less than, decreased by, fewer than, take away |
Multiplication | multiplied by, times, product of, twice |
Division | divided by, quotient of |
Tearrik was able to buy the video game he desired and he started playing right away.
In the game, timed challenges reward players with bonus points for finishing them quickly. Confused about how the bonus points are rewarded, Tearrik asked his friend Magdalena about it. She told him how the bonus points work.
Identify the variable. Then, look for keywords in Magdalena's information that indicate operations.
+or
−signs. In verbal expressions, there are words or phrases that indicate certain mathematical operations.
Key Words and Phrases | |
---|---|
Addition | added to, plus, sum of, more than, increased by, total of and |
Subtraction | subtracted from, minus, difference of, less than, decreased by, fewer than, take away |
Multiplication | multiplied by, times, product of, twice |
Division | divided by, quotient of |
Tearrik continues to enjoy playing his new game. He is focusing on collecting the challenge stars on each level.
After a weekend of playing his new game, Tearrik has to go to class. During math class, the teacher drew a square on the whiteboard.
The professor asked the class about the difference between the area of the square and its perimeter.
s=7
Calculate power
Multiply
Subtract terms
While studying math, Tearrik remembered that he drew a sign to show the prices for the shirts and the pants during his garage sale.
Since Tearrik started studying algebraic expressions, he realized that he could use variables to represent the number of items of clothing he sold. He assigned s for the shirts he sold and p for the pants he sold.
s=10, p=4
Multiply 5 by 10
Multiply 16 by 4
Add terms
Izabella is wondering how much food she feeds her two dogs.
We are asked to write an algebraic expression to represent the number of cups of food that Izabella gives her dogs in a week. Let's first write the number of cups per day. We are given that each day she gives t and b cups to her dogs.
Variable | |
---|---|
Amount of Food Given to Small Dog | t |
Amount of Food Given to Big Dog | b |
The sum of these variables is the amount eaten in a day. t + b If we want to write how many cups she gives her dogs in two days, we need to add the expression to itself. t + b + t + b = 2(t + b) We multiplied the sum of t and b by 2 to find how many cups of food Izabella gives her dogs in two days. If we follow this logic, we need to multiply the sum by 7 to find how many cups of food she gives her dogs in a week. This is because each week has 7 days. Cups of Food Per Week: 7 (t + b) This expression can also be simplified by using the Distributive Property. 7t + 7b Now we have the expression to know how many cups of food Izabella feeds her dogs in a week.
LaShay evaluated an algebraic expression when x=7. In her notes, a mistake can be found.
We are asked to determine what mistakes, if any, LaShay made when evaluating an algebraic expression. Let's evaluate the expression ourselves to see if there are any errors. We substitute 7 for the variable x and then evaluate the resulting numerical expression.
Comparing LaShay's work with our work, we can see that substituting the value for the variable was done correctly. The mistake was that LaShay added 7 and 8 instead of multiplying 7 by 3.
We can conclude that LaShay did not follow the order of operations. She had to multiply 7 by 3 first. Therefore, the answer is B.
A local game store sells video game equipment.
Let's try to write the algebraic expression ourselves. We will find how much each item costs and then we will add them. We are told that each arcade stick has a price of $ 100. Mark wants to buy a arcade sticks. This means that the amount for the arcade sticks is the product of 100 by a. Cost of Arcade Sticks 100a We know that the price of the controllers is $ 75 and that Mark wants to buy c controllers. In a similar manner, we can say that the amount for the controllers is the product of 75 by c. Cost of Controllers 75c Now we have the amounts for the arcade sticks and the controllers. Things are progressing quite well. We add the expressions to write an expression for the total amount. Total Cost 100a+ 75c This is the algebraic expression that represents how much Mark has to pay. We are done! Remember that we should always be mindful when we write the products and correctly associate the variables with the appropriate coefficients.
A group of people are buying tickets to a theme park.
We are asked for the cost of an adult ticket. We are given an algebraic expression for the total cost of tickets for a adults and c children. 50a + 26c This expression have two terms. We can see that there is a term with the variable a. 50 a + 26c We know that a represents the number of adults. This variable has a coefficient of 50. Since the expression represents the total cost, the term 50 a alone represents the cost of tickets for the adults. Cost For the Adults 50 a This cost is the product of the number of adults a and the price for each ticket. This means that each adult ticket has a price of $ 50.
We can find the term for the total cost of tickets for the children by following the same reasoning we did in Part A. This time, we need to focus on the term with the variable c.
50a + 26 c
This term is made of the variable c and the coefficient 26. Also, the term represents the cost of tickets for the adults.
Cost For the Children 26 c
This cost is the product of the number of children c and the entry price for each child. This means that each ticket has a price of $ 26.
We want to find the total cost of tickets for 4 adults and 9 children. This means that we need to evaluate the given algebraic expression when a= 4 and c = 9. Let's substitute these values and then evaluate the resulting numerical expression.
Our work indicates that the entry cost of 4 adults and 9 children is of $434.