direct variations

pflores

New member
My question says:

Which equation(s) represent a direct variation?

A) y=2x-4
B) y-4x=0
C) 2y= -3x
D) y= -2/5x
E) y= -5x+0

How do I get to the solution? Can you give me a good example?

skeeter

Senior Member
direct variation between y and x ...

y = kx + c , where k and c are any constants

stapel

Super Moderator
Staff member
Direct variation is usually taken to mean a relation of the form "y = kz", where "z" could be any sort of variable expression (such as x or sqrt[x], etc) and "k" is just a number.

Check your textbook for confirmation of the definition. Then rearrange some of the equations, so they're all in the form "y = (something)". Then see if the "something" is of the required form.

Eliz.