What is a constant of variation or constant of proportionality?

Answer 1

if y=kx, where x and y are variables, we say y is proportional to x and k is known as constant of proportionality.

Answer 2

When two variables x and y vary directly they are related by a formula y=kx, k is the constant of variation or proportionality.
When two variables x and y vary inversely ly they are related by a formula y=k/x, k is the constant of variation or proportionality.

Answer 3

If one value, y, varies when another value , x , varies, then y is said to vary as x varies.
That tells us that y and x may be written in equation form using a constant, k:-
y = kx (direct proportion)
y = k/x (inverse proportion)
y = kx² (y varies as x²)
y = kx³ (y varies as x³)
y = k√x (y varies as √x)

When values for y and x are known, k may be calculated.