Tell whether the equation represents a direct variation. If so identify the constant of variation.
y = 2x-9

Question

Tell whether the equation represents a direct variation. If so identify the constant of variation.
y = 2x-9

mikey · Answer

By direct variation, do you mean linear relationship?

anonymous · Answer

yes

mikey · Answer

Then it is direct...because it is a linear equation

mikey · Answer

The constant would be the slope.

dape · Answer

It's NOT a direct variation. If it were we could find a constant such that
$$ y=kx $$
For all y and x. Here the -9 makes this impossible.
Think of it like if you double your x, your y should be twice as large. If you triple your x, your y should be three times larger and so on.

mikey · Answer

That's very true.  I was going off the fact he said he meant linear.

dape · Answer

Yes, it's basically just terminology, which I too mix up all the time. You are right that it is linear though.