6.AT.7 Group 2 · Challenge

Practice Set · Part 1

Identify Equivalent Algebraic Expressions

Pick up where we left off

Name: Date: Group:

Where we left off

Our goal: I can show that two expressions are equivalent by simplifying and combining like terms, explain why the method works, and use it on a problem I have not seen before.

The big idea: Equivalent expressions give the same answer for every value of the variable — and you can say why it is true, and where it would stop being true.

Model to copy — Watch me

  1. Producer A wrote 3x + 2x + 10 and Producer B wrote 5x + 10. Are they equivalent?
  2. I test x = 4. For A: 3(4) + 2(4) + 10 = 12 + 8 + 10 = 30.
  3. For B: 5(4) + 10 = 20 + 10 = 30.
  4. Both give 30, and 3x + 2x is just 5x, so they are equivalent.

Start here

You did these with your group. Now do them on your own — the model above is yours to copy.

  1. 1

    Same stepsFinish what the group started. Use the model above, step for step.

    Try it together — then prove it: Let's check 2x + 3x and 5x. Try x = 2. 2(2) + 3(2) = 4 + 6 = 10, and 5(2) = 10. Same answer. So 2x + 3x and 5x are equivalent. Now prove it: say why that move had to work at all — not just that it did.
    Show your work
  2. 2

    Warm restartEvaluate 4n + 3 when n = 5.

    1. A23
    2. B35
    3. C27
    4. D45

    How do you know?

  3. 3

    Warm restartWhich expression means '7 more than a number x'?

    1. Ax + 7
    2. B7x
    3. Cx − 7
    4. D7 − x

    How do you know?

  4. 4

    Warm restartA ticket costs $9. Which expression gives the cost of t tickets?

    1. A9t
    2. Bt + 9
    3. C9 + t
    4. Dt ÷ 9

    How do you know?

6.6 Small Group · Group 2 · Practice SetPart 1 of 4
6.AT.7 Group 2 · Challenge

Practice Set · Part 2

Identify Equivalent Algebraic Expressions

Keep going

You answered these out loud. Now write them.

Answer, then say how you know — the reason is the part that counts.

  1. 5

    Think it throughSimplify 4h + 2h + 30.

    1. A6h + 30
    2. B6h + 30h
    3. C36h
    4. D4h + 32

    Why is that the answer?

  2. 6

    Think it throughAre the two pricing formulas equivalent?

    1. AYes — 4h + 2h + 30 simplifies to exactly 6h + 30
    2. BNo — Client A pays more
    3. CNo — Client B pays more
    4. DOnly when h = 0

    How do you know? Give a second reason as well.

  3. 7

    Think it throughTest it: what does each expression equal when h = 5?

    1. ABoth equal 60
    2. BBoth equal 90
    3. CA = 60 and B = 55
    4. DA = 50 and B = 60

    Explain your thinking. What would have to change for a different choice to be right?

  4. 8

    Back to the modelHow did you decide which expressions belong in the same group? What strategies did you use?

6.6 Small Group · Group 2 · Practice SetPart 2 of 4
6.AT.7 Group 2 · Challenge

Practice Set · Part 3

Identify Equivalent Algebraic Expressions

Words and reasoning

Word bank · Banco de palabras

Equivalent Expressions (Expresiones equivalentes)Equivalent (Equivalente)Simplify (Simplificar)Like Terms (Términos semejantes)Combine (Combinar)Coefficient (Coeficiente)

Use the words

Fill each blank with a word from the bank.

Explain the thinking

  1. 9

    Find the mistakeAnother student made this exact mistake in this lesson. Explain why it is wrong, then write what they should have done.

    The mistake: A common mistake in Equivalent Expressions is adding the exponents instead of the coefficients when combining like terms — writing 3x + 2x as 5x² instead of 5x.
  2. 10

    Say moreHow can you prove 2(n + 4) and 2n + 8 are equivalent? What two strategies could you use?

  3. 11

    Write your ownWrite your own problem about this situation, then solve it and show the answer. The situation: The same square is shown two ways — broken into green strips and yellow unit squares on the left, and as one whole red square on the right.

    Show your work
6.6 Small Group · Group 2 · Practice SetPart 3 of 4
6.AT.7 Group 2 · Challenge

Practice Set · Part 4

Identify Equivalent Algebraic Expressions

Show what you know

Last check

These two come from Lesson 6.5. If they are shaky, that is the lesson to revisit — not this one.

  1. 12

    Show what you knowExplain your thinking — Which expression is equivalent to 6n + 4 + 3n − 1?

    1. A9n + 3
    2. B9n + 5
    3. C63n
    4. D18n + 4

    Explain your choice.

  2. 13

    From Lesson 6.5Explain your thinking — A club orders one $4.25 shirt for each student plus a one-time $23.50 shipping fee. Write the expression for s students, then find the cost for 30 students.

    1. A4.25s + 23.50; for s = 30 the cost is $151.00
    2. B4.25s + 23.50; for s = 30 the cost is $832.50
    3. C4.25 + 23.50s; for s = 30 the cost is $709.25
    4. D27.75s; for s = 30 the cost is $832.50

    How do you know?

  3. 14

    From Lesson 6.5In 25 + 8h, what is the coefficient?

    1. A8
    2. B25
    3. Ch
    4. D25h

    How do you know?

Be honest — this tells your teacher what to do next

I can…Not yetGetting thereGot it
I can show that two expressions are equivalent by simplifying and combining like terms, explain why the method works, and use it on a problem I have not seen before.
I can explain why it works: Equivalent expressions give the same answer for every value of the variable — and you can say why it is true…
I can justify my answer to a skeptic and connect it to a second strategy or representation.

One question I want to ask my group next time