9th grade · Math · Unit 3 of 17
Expressions
Build, compare and match
What your child practices
Writing an expression for a pattern or a sentence, deciding which expressions are equivalent, expanding brackets, and collecting like terms.
Washington State Learning Standards learning standard: M.HS.Q.ASSE.1 · building and interpreting expressions in context
How we explain it
Children can open this short lesson before they practice.
- An expression uses letters and numbers: 3n + 2.
- Equivalent expressions have the same value for every number.
- Expand with the distributive property: 2(x + 3) = 2x + 6.
Example: Expand 3(x + 4). 3 × x = 3x. 3 × 4 = 12. Answer: 3x + 12
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
Which expression is equivalent to 5(x + 7)?
- x + 35
- 5x + 7
- 5x + 35
- 5x + 12
5x + 35
Hint: Multiply both terms inside the brackets by 5: 5 × x = 5x and 5 × 7 = 35.
Question 2
If n = 6, what is the value of 2n − 9?
answer box
3
Hint: Replace n with 6: 2 × 6 − 9 = 3.
Question 3
Ana has 9 fewer than 5 times the number of cards Leo has. If Leo has n cards, which expression gives the number Ana has?
- 5(n − 9)
- 9n − 5
- 9 − 5n
- 5n − 9
5n − 9
Hint: "5 times" Leo's number is 5n. "9 fewer" is taken away after that: 5n − 9.
Question 4
Which expression is NOT equivalent to 4x + 12?
- 12 + 4x
- x + 3x + 12
- 4(x + 12)
- 4(x + 3)
4(x + 12)
Hint: Expand each one. 4(x + 3) = 4x + 12, but 4(x + 12) = 4x + 48.
Question 5
Figure n in a pattern uses 3n + 1 tiles. How many tiles does figure 20 use?
answer box
61
Hint: Replace n with 20: 3 × 20 + 1 = 61.
Question 6
Which expression gives the number of tiles in figure n?
Figure n Tiles 1 4 2 7 3 10 4 13 - 4n
- 3n + 1
- n + 3
- 3n − 1
3n + 1
Hint: The tiles grow by 3 each figure, so the n-term is 3n. Figure 1 has 4 tiles, so add 1.