Graph

Constant of Proportionality

Explore how y = kx creates a straight line through the origin

Constant k (slope):

k = 2.0

X Value:

x = 5.0

Constant (k)

2.0

X Value

5.0

Y Value

10.0

Ratio (y/x)

2.0

y = 2.0x

What is the Constant of Proportionality?

The constant of proportionality (k) is the constant ratio between two proportional quantities. In the equation y = kx, k represents this constant.

Key Properties:

• The graph always passes through the origin (0, 0)

• The value k represents the slope of the line

• For any point on the line, y/x always equals k

• If k increases, the line becomes steeper

Real-world examples: Speed (distance = speed × time), Unit price (total cost = price × quantity), Currency exchange rates