Answer:
Graph b
Step-by-step explanation:
Direct variation means "y varies directly as x”:
Direct variation equation:
[tex]y=kx[/tex]
where k is the (non-zero) constant of variation.
Note, therefore, that a direct variation equation passes through the origin, as when x = 0:
[tex]\implies y=k(0) \implies y=0[/tex]
Graph a
y does not change as x varies.
Therefore this graph does not model a direct variation.
Graph b
As x gets bigger, so does y. As x gets smaller, so does y.
The line passes through the origin (0, 0).
Therefore this graph models a direct variation.
Graph c
x does not change as y varies.
Therefore this graph does not model a direct variation.
Graph d
As x gets bigger, so does y. As x gets smaller, so does y.
However, the line does not pass through the origin (0, 0).
Therefore this graph does not model a direct variation.
