Question

PLEASE HELP!!!!!!!!!



Which is the direct linear variation equation for the relationship?

y varies directly with x and y = 12 when x = 4.


A.
y = x – 8

B.
y = 2x + 4


C.
y = x + 8

D.
y = 3x

Answer 1

two hints:

direct variation equations are ALWAYS in the form y = kx

make sure that the point (4,12) lies on the line (so plug in both values and see if you get a true equation or not)

Answer 2

also, in y = kx, the k is some constant yet to be determined

Answer 3

But all the equations except A are all equal to 12

Answer 4

keep the form y = kx in mind

and you have to make sure that plugging in x = 4 gives you y = 12

Answer 5

both facts have to be true

Answer 6

yes they both are true on b, c, and d

Answer 7

A is not true

Answer 8

you sure? look at the form I gave you again

Answer 9

Ohhhhh its D right? It has to be in this form y = kx

Answer 10

correct, in this case, k = 3

Answer 11

basically, 4 directly scales to 12 (multiply by 3)

there are no addition/subtraction operations done afterwards...otherwise, it's not direct scaling

Answer 12

that's how I remember direct variation

Answer 13

ok

Answer 14

can you help me on my other question?