Writing y = kx, step by step
Once the constant of proportionality is known, the whole relationship fits in one short equation: y = kx.
The question
x4679y24364254y =x
Write the equation for the table in the form y = kx.
x: 4, 6, 7, 9 y: 24, 36, 42, 54
x4679y24364254
24÷4=6
36÷6=6
y=6x
- In a proportional table every y is its x times the SAME number — the constant of proportionality. Find it by dividing a y by its own x.
- Take the first column: 24 ÷ 4 = 6.
- Check another column so it is not a fluke: 36 ÷ 6 = 6. Every column gives 6, so the constant is 6.
- So the equation is y = 6x — it says "each y is x times 6".
How it works.
- 01
In a proportional table every y is its x times the SAME number — the constant of proportionality. Find it by dividing a y by its own x.
- 02
Take the first column: 24 ÷ 4 = 6.
- 03
Check another column so it is not a fluke: 36 ÷ 6 = 6. Every column gives 6, so the constant is 6.
- 04
So the equation is y = 6x — it says "each y is x times 6".