Question

Determine whether y varies directly with x. if so, find the constant of variation k and write the equation.
Ill include the table, but I just need to know what formula to use.

Answer 1

I know the formula is either y=kx or k=y/x. I tried k=y/x but I didn't get the same answers for each pair.

Answer 2

you use y = k*x

Answer 3

you can solve for k to get k = y/x if you want

Answer 4

notice how for the first row we get

k = y/x

k = 11/7

and for the second row we get

k = y/x

k = 13/8

but those two values aren't the same, so this means that y does NOT vary directly with x

Answer 5

I haven't used that formula before.
For example, for the first pair, do I:
11=k*7 ?

Answer 6

then you solve for k

Answer 7

So, since y doesn't vary directly with x I cant continue doing the problem?

Answer 8

that is correct

k is not the same each time, so y doesn't vary directly with x and because of that you can't find the equation in the form y = k*x

Answer 9

I see. so, to show my work Im going to solve each pair using the formula k=y/x and after Im going to say y does not vary directly with x so I cant find the equation in the form of y=k*x. ?

Answer 10

yes all you need are 2 rows or two pairs to show that k is different

Answer 11

you don't need to work with every pair unless you want to

Answer 12

Alright, thank you!

Answer 13

you're welcome