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Simplifying and writing expressions 1: length and perimeter

This is a beginner lesson about simplifying algebraic expressions, for grades 6-7.

I model simple algebraic expressions using line segments of varying lengths, and thus help you understand HOW TO simplify those types of expressions. For example, y + y + y simplifies to 3y because it is modeled as 3 "sticks" of y units long. Another easy example: a + a + b simplifies to 2a + b, and is modeled by 2 sticks "a" units long and one stick "b" units long.

You will also learn how to omit unnecessary multiplication signs from expressions and how to simplify expressions such as a · 5 · 3.

Later in the lesson I explain what a "term" means in algebra: a TERM can include multiplications, divisions, variables, and numbers, but not additions and subtractions. An algebraic expression can have several terms, which are separated by additions or subtractions.

Lastly, we form and simplify an expression for the perimeter of various shapes.

See also

Math Mammoth Expressions and Equations — a short workbook where you can find worksheets that match this lesson.

Math Mammoth Grade 6 Curriculum — again, contains worksheets to match this lesson.

Math Mammoth Grade 7 curriculum (pre-algebra)

Back to pre-algebra videos index

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