Question

What is the direct variation equation if y varies directly with x and y = –9 when x = –45?

A: y = 1/5x

B: y = -5x

C: y = 5x

D: y = -1/5x

Answer 1

y = kx

Plug in what we know:

'y = -9' 'x = -45'

-9 = k(-45)

-9 = -45k

Divide -45 to both sides.

Answer 2

Wait, so -9 divided by -45?

Answer 3

Yep.

Answer 4

36?

Answer 5

No..idk how you got that..try again. -9 / -45

Answer 6

my calculator glitched, sorry

Answer 7

It's fine

Answer 8

0.2?

Answer 9

Yes, and 0.2 is the same thing as 2/10 which simplifies to 1/5.

So the constant of variation is 1/5.

So we write it like:

y = 1/5x

Answer 10

Thank you

Answer 11

No problem.