Subtract and simplify expressions.
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This lesson includes problems such as $${3x - (6 + 8x) }$$ but does not include problems such as
$${3x - 2(6 + 8x)}$$, where a multiple of an expression is being subtracted. This will be covered in Lesson 7 and Lesson 8. The concept of distributing a negative through a parentheses group can be challenging for students, so this lesson focuses on students understanding that when an expression is subtracted, every term in the expression is subtracted, not just the first term.
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Consider the numerical expression: $${12-(3+4)}$$
The expression is rewritten so it does not include parentheses. Which expression will give the same value as the original expression? Explain your reasoning for each one.
$${12-3+4}$$ $${12-3-4}$$
Subtract: $${(3x+5y-4)-(4x+11)}$$
Grade 7 Mathematics > Module 3 > Topic A > Lesson 2 of the New York State Common Core Mathematics Curriculum from EngageNY and Great Minds. © 2015 Great Minds. Licensed by EngageNY of the New York State Education Department under the CC BY-NC-SA 3.0 US license. Accessed Dec. 2, 2016, 5:15 p.m..
Match each subtraction problem on the left with the equivalent simplified expression on the right.
A. $$5x-(3x+1)$$ |
1. $$-8x-1$$ |
B. $$5x-(-3x-1)$$ |
2. $$-2x+1$$ |
C. $$-5x-(3x+1)$$ |
3. $$2x-1$$ |
D. $$-5x-(-3x-1)$$ |
4. $$8x+1$$ |
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The following resources include problems and activities aligned to the objective of the lesson that can be used to create your own problem set.
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Two expressions are given below.
Expression A: $${5q-r}$$
Expression B: $${ -2q+3r-4}$$
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