Proportions

Question 1

What do we write if two quantities x and y are directly proportional?

Answer 1

y ∝ x
hence y=kx and k being proportionality constant

Question 2

What do we write of two quantities x and y are inversely proportional?

Answer 2

y ∝ 1/x
hence y ∝ k/x or xy = k

Question 3

To be directly proportional, the graph of x against y must:

Answer 3

• Be a straght line.
• Cross through the point of origin (0,0).