suppose y varies directly with X write a direct variation equation that relates X to Y
y=-10 when x=2
A.y=-5x
B.y=-1/5x
C.y=5x
D.y=1/5x

Question

suppose y varies directly with X write a direct variation equation that relates X to Y
y=-10 when x=2
A.y=-5x
B.y=-1/5x
C.y=5x
D.y=1/5x

mathstudent55 · Answer

A direct variation is written this way:
If y varies directly with x, then y = kx.

mathstudent55 · Answer

Start by writing y = kx

Now you need to find what the value of k is for your specific direct variation.
To do that, replace x and y in y = kx with the x- and y-coordinates, respectively, of your given point.
Then solve for k.
Finally, rewrite y = kx with the value of k you found replacing k.

cookiemonster18 · Answer

I think its B, am I correct? @mathstudent55

cookiemonster18 · Answer

@Vocaloid

mathstudent55 · Answer

Let's see:

$y = kx$

Now we use point (2, -10), with x = 2 and y = -10.

$-10 = (k)(2)$

$2k = -10$

$k = -5$

$y = -5x$

You are correct. The answer is B.