8th grade · Math · Unit 10 of 19
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.
New York State Learning Standards learning standard: NY-8.F.3; NY-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.
- A table pairs each x with a y.
- Plot each pair as a point. A straight line means a linear relation.
- 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 New York
In the New York State Learning Standards, this is unit 10 of 19 in 8th grade Math, after Similarity & Scale 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.
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
The ordered pair (?, 2) is on the line y = 2x + 6. What is the missing x-value?
answer box
-2
Hint: Put y = 2 in the equation: 2 = 2x + 6. Undo the addition, then divide by 2: x = -2.
Question 2
Which equation matches the table of values?
x y 1 9 2 14 3 19 4 24 - y = 6x + 4
- y = 5x + 4
- y = 5x − 4
- y = 4x + 5
y = 5x + 4
Hint: Test the first row: x = 1 gives y = 9. Only y = 5x + 4 works for every row.
Question 3
Which ordered pair is on the graph of y = 4x + 3?
- (2, 8)
- (2, 11)
- (2, 10)
- (2, 12)
(2, 11)
Hint: Substitute x = 2: 4 × 2 + 3 = 11.
Question 4
For the relation y = 6x + 2, what is y when x = -1?
answer box
-4
Hint: Replace x with -1: 6 × (-1) + 2 = -4.
Question 5
In the relation y = 3x − 2, by how much does y change each time x increases by 1?
answer box
3
Hint: The number multiplying x is 3, so y changes by 3 for each step of 1 in x.
Question 6
The table shows a linear relation. What number goes in place of the ?
Table of values x y 0 3 1 7 2 11 3 15 4 ? answer box
19
Hint: Look at how y changes each time x goes up by 1. It changes by 4, so y = 19 when x = 4.