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8th grade · Math · Unit 9 of 17

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.

Alaska content standards learning standard: 8.F.3; 8.F.4 · linear functions of the form y = mx + b, their tables and graphs

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 Alaska

In the Alaska content standards, this is unit 9 of 17 in 8th grade Math, after Angle Detective and before Equations with Brackets.

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: Alaska Department of Education and Early Development

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 = 3x + 4?

    • (6, 21)
    • (6, 18)
    • (6, 22)
    • (6, 23)

  2. Question 2

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

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

  3. Question 3

    The table shows a linear relation. What number goes in place of the ?

    Table of values
    xy
    0-5
    1-3
    2-1
    31
    4?

    answer box

  4. Question 4

    Which equation matches the table of values?

    xy
    14
    27
    310
    413
    • y = 3x − 1
    • y = 3x + 1
    • y = 1x + 3
    • y = 4x + 1

  5. Question 5

    The ordered pair (?, 31) is on the line y = 4x + 3. What is the missing x-value?

    answer box

  6. Question 6

    In the relation y = 3x + 1, by how much does y change each time x increases by 1?

    answer box

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