I don't know how i got this question wrong.

In a direct variation, the constant of proportionality is -3.
Which of the following would be its equation?
A) y = x - 3
B) -3y = x
C) y = -3x
D) -3 = xy

I put A as my answer... but it says the answer is C! How is C the answer?
PLZ keep ur explanation simple.
Thanks for helping me,
Scar

3 answers

direct variation means y is proportional to x
(if you double x, you double y)

algebraically that means;

y = k * x where k is a constant which they call "constant of proportionality" and I just call "k" :)

here
y = (-3) * x or -3x

thnx Damon 😊

You are welcome.