Question

Is a proportional function f(x) = 5x linear? Why or why not? Explain with an example.

Answer 1

Given two variables x and y, y is directly proportional to x (x and y vary directly, or x and y are in direct variation) if there is a non-zero constant k such that

   y = kx,

The relation is often denoted, using the ∝ symbol, as

   y ∝ x

in this case k = 5/1