In this Grade 7 lesson from Reveal Math, Accelerated, students learn how to add and subtract linear expressions by combining like terms and applying the additive inverse property. Using algebra tiles and properties of operations, they simplify expressions such as (2x + 3) + (5x − 5) and (x + 150) − (0.05x + 50) in real-world contexts like mosaic design and budgeting. The lesson builds fluency with rewriting subtraction as addition and regrouping terms to produce expressions in simplest form.
Section 1
Concept: Adding Linear Expressions
To add linear expressions, we remove parentheses and combine like terms.
Like terms have the same variable with the same exponent.
For linear expressions, we combine constant terms together and variable terms with the same variable together.
To add like terms, we add their numerical coefficients.
Section 2
Concept: Subtracting by Adding the Opposite
When subtracting linear expressions, you can rewrite subtraction as adding the opposite (additive inverse).
For any linear expressions and , we have . The opposite of an expression changes the sign of every term.
Section 3
Level Up: Expressions with Fractional Coefficients
The rules for adding and subtracting do not change when fractions appear! To combine terms with fractional coefficients, follow the exact same steps, but find a Common Denominator (LCD) for your matching variables before you add or subtract the numerators.
Do not let fractions cause panic! Treat the variable just like a label. Put the terms next to each other, put the normal numbers next to each other, and handle them as two separate mini-math problems. Finding the common denominator is just making sure you are comparing "apples to apples" before you combine them.
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Section 1
Concept: Adding Linear Expressions
To add linear expressions, we remove parentheses and combine like terms.
Like terms have the same variable with the same exponent.
For linear expressions, we combine constant terms together and variable terms with the same variable together.
To add like terms, we add their numerical coefficients.
Section 2
Concept: Subtracting by Adding the Opposite
When subtracting linear expressions, you can rewrite subtraction as adding the opposite (additive inverse).
For any linear expressions and , we have . The opposite of an expression changes the sign of every term.
Section 3
Level Up: Expressions with Fractional Coefficients
The rules for adding and subtracting do not change when fractions appear! To combine terms with fractional coefficients, follow the exact same steps, but find a Common Denominator (LCD) for your matching variables before you add or subtract the numerators.
Do not let fractions cause panic! Treat the variable just like a label. Put the terms next to each other, put the normal numbers next to each other, and handle them as two separate mini-math problems. Finding the common denominator is just making sure you are comparing "apples to apples" before you combine them.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter