Grade 8 · Math · Unit 6 of 14
Tables, Graphs & Linear Relations
Find missing values in y = mx + b
What your child practises
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.
Prince Edward Island Curriculum curriculum outcome: Patterns and Relations · tables of values and graphs of linear relations like y = 3x + 2
How we explain it
Children can open this short lesson before they practise.
- 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
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
In the relation y = 3x − 4, 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 2
Which ordered pair is on the graph of y = 5x + 3?
- (4, 24)
- (4, 20)
- (4, 22)
- (4, 23)
(4, 23)
Hint: Substitute x = 4: 5 × 4 + 3 = 23.
Question 3
The ordered pair (?, 24) is on the line y = 4x + 4. What is the missing x-value?
answer box
5
Hint: Put y = 24 in the equation: 24 = 4x + 4. Undo the addition, then divide by 4: x = 5.
Question 4
For the relation y = 4x + 3, what is y when x = 7?
answer box
31
Hint: Replace x with 7: 4 × 7 + 3 = 31.
Question 5
The table shows a linear relation. What number goes in place of the ?
Table of values x y 0 -1 1 2 2 ? 3 8 4 11 answer box
5
Hint: Look at how y changes each time x goes up by 1. It changes by 3, so y = 5 when x = 2.
Question 6
Which equation matches the table of values?
x y 1 9 2 12 3 15 4 18 - y = 6x + 3
- y = 3x − 6
- y = 3x + 6
- y = 4x + 6
y = 3x + 6
Hint: Test the first row: x = 1 gives y = 9. Only y = 3x + 6 works for every row.