What you’ll learn
Interpret points on proportional graphs.
Key idea
In a proportional situation, y = kx, so the point says that x input units correspond to y output units. The order matters: the horizontal coordinate is x and the vertical coordinate is y.
For example, if x is minutes and y is liters, (4, 12) means 12 liters after 4 minutes. The constant rate is 12/4 = 3 liters per minute. The point describes one pair; the equation and rate explain how other points are related.
Worked example
Enter the exact value or ordered values in the format requested below.
On this no-fee notebook graph, x is notebooks and y total dollars. Enter P's numerical total cost.
Marked coordinates: P=(6, 24); U=(1, 4); O=(0, 0).
- Horizontal x measures notebook count, while vertical y measures total dollars.
- P=(6,24) therefore means 6 notebooks cost $24, consistent with unit price $4.
Answer: 24
Quick Check
Relate the graph used in 'Interpret points on proportional graphs' to an equation, table, transformation, or verbal description.
Connect point P=(6,48) on y=8x with x notebooks and y dollars to a contextual interpretation.