How can you determine if a linear relationship is a direct variation from an equation? a table? a graph? (Is the answer comparing the ratios to check for a common ratio?)

Question

How can you determine if a linear relationship is a direct variation from an equation? a table?  a graph? (Is the answer comparing the ratios to check for a common ratio?)

hartnn · Answer

Equation:
a linear relationship is of the form $y = mx+c$
where as the direct variation is $y = mx$

see the difference?

from graph, if the line passes through the origin, then its a direct variation :)