Subscribe

8th grade · Math · Unit 6 of 15

Tables, Graphs & Linear Relations

Find missing values in y = mx + b

What your child practices

Using an equation like y = 3x + 2 to build a table of values, find a missing x or y, and describe how the variables change together.

Texas Essential Knowledge and Skills (TEKS) teks student expectation: 8.5(B); 8.5(I) · linear relationships of the form y = mx + b in tables, graphs and equations

How we explain it

Children can open this short lesson before they practice.

  1. A table pairs each x with a y.
  2. Plot each pair as a point. A straight line means a linear relation.
  3. Look at how y changes each time x goes up by 1.

Example: x = 0, 1, 2 gives y = 3, 5, 7. What is y when x = 3? y goes up by 2 each time. 7 + 2 = 9. Answer: 9

Tables, Graphs & Linear Relations in Texas

In the Texas Essential Knowledge and Skills (TEKS), this is unit 6 of 15 in 8th grade Math, after Slope & Rate of Change and before Functions.

Gradelings describes a child's practice on this unit as Beginning, Approaching, Meeting or Exceeding (Four practice steps). That reflects practice, not a report-card mark: the teacher decides the mark.

Source: Texas Education Agency (TEA)

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    Which ordered pair is on the graph of y = 5x + 2?

    • (7, 36)
    • (7, 37)
    • (7, 38)
    • (7, 35)

  2. Question 2

    For the relation y = 2x − 2, what is y when x = 1?

    answer box

  3. Question 3

    In the relation y = 6x + 9, by how much does y change each time x increases by 1?

    answer box

  4. Question 4

    Which equation matches the table of values?

    xy
    18
    213
    318
    423
    • y = 6x + 3
    • y = 5x + 3
    • y = 3x + 5
    • y = 5x − 3

  5. Question 5

    For the relation y = 6x + 7, what is y when x = -2?

    answer box

  6. Question 6

    A graph shows the number of notebooks bought (1, 2, 3 and so on) and the total cost. Should the points be joined with a line?

    • Yes. Graphs of linear relations must always be joined.
    • No. You can only buy a whole number of notebooks, so only separate points make sense.
    • No. A linear relation cannot be graphed.
    • Yes. Every point on the line is a possible number of notebooks.

More 8th grade