Evaluating Expressions
LESSON B3
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I can evaluate expressions that represent real-world situations and I can combine like terms to simplify expressions.
Student Objective
What are some social causes you care about?
�Write about a cause that �is most important to you �and why it is important.
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Some common social causes that students and adults alike �care about include:
Discussion Norms
This is a placeholder to include co-developed negotiated Norms
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Another Social Cause is the Healthy Food Movement
This movement broadly seeks to increase better eating in the United States. The movement emphasizes locally grown foods and more greens. The challenge they are currently facing is how to work with the fast-paced American lifestyle in which grab-and-go foods are the norm.
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Another issue this cause cares about is “food-insecurity” �which is the inability to access nutritious foods; �cost is the most common barrier to accessing nutritious foods.
As a result, many Americans choose �to buy cheaper foods to fit their �budget which often do not have �all of the nutrition components �they need and are high in �sodium, fats, and sugars.
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2. The Smith family placed an order using only value menu items pictured above. Based on the expression below, can you tell what they ordered? Explain your thinking to your partner.
190 (3) + 410 (2) + 240 (2) + 430(4)
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3. You find out the Smith family is a family of 4.
Given that the average person should have a 2,000 calorie diet, do you think this family is consuming a reasonable amount of calories for dinner? Explain your thinking to your partner.
190 ( 3) + 410 (2) + 240 (2) + 430(4)
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4. Take a look at the Group section of the Taco Bell Menu.
Can you tell what was ordered from the group menu?
Which expression helped you discover the order?
3p
3(4t + 4b)
(4t + 4b) + (4t + 4b) +(4t + 4b)
12t + 12b
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5. Take the Group section of the Taco Bell Menu further...
3p
3(4t + 4b)
(4t + 4b) + (4t + 4b) +(4t + 4b)
12t + 12b
12
3p
3(4t + 4b)
(4t + 4b) + (4t + 4b) +(4t + 4b)
12t + 12b
Equivalent Expressions
The expression in the second line is equivalent to the expression in the third line.
The 3 in front of the parentheses indicates 3 groups of (4t + 4b), therefore the third expression is the expanded form of the second expression.
3(4t + 4b)
(4t + 4b) + (4t + 4b) +(4t + 4b)
1 2 3
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3p
3(4t + 4b)
(4t + 4b) + (4t + 4b) +(4t + 4b)
12t + 12b
Equivalent Expressions
The expression in the third line is also equivalent to the expression in the fourth line. The like terms in the third expression are combined using addition to simplify the expression to its final form in line 4.
(4t + 4b) + (4t + 4b) +(4t + 4b)
(4t + 4b) + (4t + 4b) +(4t + 4b)
4t + 4t + 4t + 4b + 4b + 4b
12t + 12b
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Equivalent Expressions
Why can’t we add the coefficients to simplify the expression further?
Let’s remind ourselves of what the terms represent in the original context:
The variable t represents the calories in a taco
The variable b represents the calories in a burrito
The coefficient 12 represents the quantity of each menu item in the pack
Therefore, we cannot combine the final two terms because the variables are different and represent different quantities
Let’s Practice Combining Like Terms
Simplify each expression below by combining like terms
6. 3x + 2y + 2y
7. 5x - 2x + y + y + 3x
8. 1y + 3y - 5 + 4x - 4y
9. 3z + z + 6 + 8x - 1
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Summary
10. Think about the fast food menus you explored today. Is there anything that you have a new outlook about or something you may do differently in the future?
11. How did your knowledge of like and unlike terms help you identify equivalent expressions?
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