Practice Set · Part 1
Identify Equivalent Algebraic Expressions
Pick up where we left off
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
- Producer A wrote 3x + 2x + 10 and Producer B wrote 5x + 10. Are they equivalent?
- I test x = 4. For A: 3(4) + 2(4) + 10 = 12 + 8 + 10 = 30.
- For B: 5(4) + 10 = 20 + 10 = 30.
- 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
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
Warm restartEvaluate 4n + 3 when n = 5.
- A23
- B35
- C27
- D45
How do you know?
- 3
Warm restartWhich expression means '7 more than a number x'?
- Ax + 7
- B7x
- Cx − 7
- D7 − x
How do you know?
- 4
Warm restartA ticket costs $9. Which expression gives the cost of t tickets?
- A9t
- Bt + 9
- C9 + t
- Dt ÷ 9
How do you know?
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.
- 5
Think it throughSimplify 4h + 2h + 30.
- A6h + 30
- B6h + 30h
- C36h
- D4h + 32
Why is that the answer?
- 6
Think it throughAre the two pricing formulas equivalent?
- AYes — 4h + 2h + 30 simplifies to exactly 6h + 30
- BNo — Client A pays more
- CNo — Client B pays more
- DOnly when h = 0
How do you know? Give a second reason as well.
- 7
Think it throughTest it: what does each expression equal when h = 5?
- ABoth equal 60
- BBoth equal 90
- CA = 60 and B = 55
- DA = 50 and B = 60
Explain your thinking. What would have to change for a different choice to be right?
- 8
Back to the modelHow did you decide which expressions belong in the same group? What strategies did you use?
Practice Set · Part 3
Identify Equivalent Algebraic Expressions
Words and reasoning
Word bank · Banco de palabras
Use the words
Fill each blank with a word from the bank.
- Expressions with the same value for ___ allowed number are equivalent.
- Expressions that always have the same value are ___.
- Rewriting an expression in a shorter form that is still equal to it is to ___ it.
- Terms with the same variable raised to the same power, like 4x and 9x, are ___.
Explain the thinking
- 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. - 10
Say moreHow can you prove 2(n + 4) and 2n + 8 are equivalent? What two strategies could you use?
- 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
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.
- 12
Show what you knowExplain your thinking — Which expression is equivalent to 6n + 4 + 3n − 1?
- A9n + 3
- B9n + 5
- C63n
- D18n + 4
Explain your choice.
- 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.
- A4.25s + 23.50; for s = 30 the cost is $151.00
- B4.25s + 23.50; for s = 30 the cost is $832.50
- C4.25 + 23.50s; for s = 30 the cost is $709.25
- D27.75s; for s = 30 the cost is $832.50
How do you know?
- 14
From Lesson 6.5In 25 + 8h, what is the coefficient?
- A8
- B25
- Ch
- D25h
How do you know?
Be honest — this tells your teacher what to do next
| I can… | Not yet | Getting there | Got 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