CCSS.Math.Content.HSA-APR.D.7

MathGrades 9–12Arithmetic with Polynomials and Rational Expressions

The Standard

(+) Understand that rational expressions form a system analogous to the rational numbers, closed under addition, subtraction, multiplication, and division by a nonzero rational expression; add, subtract, multiply, and divide rational expressions.

Common Core State Standards for Mathematics

Teacher's field guide

What This Standard Means

What Students Need to Do

Students treat algebraic fractions much like numerical fractions. They find common denominators, factor and cancel valid factors, use reciprocals for division, and track values that make denominators zero.

What Mastery Looks Like

Students correctly simplify sums, differences, products, and quotients of algebraic fractions. They show factoring and common-denominator steps, state excluded values, and recognize when an operation is undefined.

Common Misconceptions

Students may add denominators when adding fractions or cancel terms across addition. They may forget to multiply by the reciprocal when dividing. They often omit values that make an original denominator zero.

How to Assess It

Give this exit ticket: Simplify 2/x + 3/(x + 1), then divide the result by 1/x and state all excluded values.

Lesson moves

Ways to Teach It

  1. Give groups rational-expression cards and operation cards; students combine each pair, simplify the result, and record excluded values.

  2. Ask students to explain how adding 2/3 and 1/4 is similar to adding 2/x and 1/(x + 1).

  3. Play a matching game where students pair unsimplified expressions with simplified forms and domain restrictions.

  4. Model two machines working together using rates 1/x and 1/(x + 2), then simplify their combined work rate.

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Printable HSA-APR.D.7 Worksheet

Preview of the CCSS.Math.Content.HSA-APR.D.7 printable worksheet

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Learning progression

Where This Standard Sits

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