Question

I asked this question three days ago and no one has helped me with it:( Im seriously confused on this and I have a quiz on this tomorrow:( You dont have to give me the answer. Just help me FULLY answer the question please!
Determine whether y varies directly with x. If so, find the constant of variation k and write the equation.

Answer 1

y = kx

substitute the first pair (4,6.4) into the equation and solve for k. then use substitute the second pair (7,11.2) and k into the equation and see if it's true. if it's true, then y varies directly with x

Answer 2

So i would write it "6.4=4 x k"

Answer 3

yea, or 6.4 = 4k

Answer 4

you know how to solve for k right?

Answer 5

no....i think this is why im so confused

Answer 6

ok, well to get k by itself on one side of the equation, just divide both sides by 4

Answer 7

so k=1.6?

Answer 8

yep :)

Answer 9

So thats all its looking for, is for me too solve all of the numbers?!

Answer 10

no...they already gave you all the solutions, all you're doing is finding if y varies directly with x and if it does, write the equation

Answer 11

since you found out what k equals, you have to see if it's true for the next set. so just plug in the pairs and k into y = kx

Answer 12

How do I know if it varies or not?

Answer 13

by doing what i just posted lol

Answer 14

So it works with the first one right!?! Sorry I had typed that before you posted that!

Answer 15

yea, it works with the first one, but does it work with second?

Answer 16

if it works with the second, chances are it works for all of them. but if you want to check in all of them to make sure, then go ahead

Answer 17

have you checked yet?

Answer 18

Wair how do i know if it doesnt work?

Answer 19

if you plug in the numbers for k and x, and they DON'T equal y, then it doesn't work

Answer 20

I got 1.6 again

Answer 21

ok, i'm guessing you did it right. do you know what our equation will be?

Answer 22

you mean like the 11.2/7=7/7 x k?

Answer 23

how did you get that?

Answer 24

this is the equation for when they directly vary. y = kx

Answer 25

k is our constant

Answer 26

WAIT! hold on now im confused. Because of r16=10k, my solution is 8/5

Answer 27

i don'y know where "r16 = 10k" came from?

Answer 28

oh you mean 16 = 10k?

Answer 29

Yeah sorry, I get excited and type really fast D:

Answer 30

if by "solution" you mean what k equals, then i don't know how you got 8/5...can you tell me what you're doing?

Answer 31

that way i can tell you what you're doing wrong, and what you're supposed to be doing :/

Answer 32

oh wait, 8/5 = 1.6

Answer 33

i see now

Answer 34

so you're right then. k would equal 8/5 or 1.6

Answer 35

Ok so i though you told me to go throw the tabel and solve for k. So I did the first set "4,6.4" and got 1.6 for k, then i did the second set "7,11.2" and got 1.6 for k, then when i solved the third set "10,16" for k i got 8/5

Answer 36

yes. 8/5 and 1.6 are the same thing, so k = 1.6. so all you have to do is substitute 1.6 for k in our original equation "y = kx

Answer 37

"

Answer 38

and that would you give you the equation you need for your answer

Answer 39

what's the equation?

Answer 40

y=1.6x???

Answer 41

yep, that's right :)

Answer 42

So thats all I have to do?

Answer 43

"Determine whether y varies directly with x." it does, we checked.

"If so, find the constant of variation k and write the equation." k = 1.6. y = 1.6x

that's all :)

Answer 44

Ohhh I got it! Ok thank you so much, its funny once its brooken down it makes sense(X

Answer 45

no problem :)