Question

Suppose y varies directly with x. If y = 6 when , find x when y = 15 .
5
-5
-1/5
1/5

Answer 1

@texaschic101

Answer 2

I do it a little bit different then most people....and this way only works on direct variation.
Oh...wait...what is x when y = 6 ?

Answer 3

yes

Answer 4

there is a number missing in your problem. What is x when y = 6 ?

Answer 5

Oh sorry -2

Answer 6

I set it up as a proportion.
6/-2 = 15/x -- (6 to -2 = 15 to x)
cross multiply
(6)(x) = (15)(-2)
6x = -30 -- divide both sides by 6
x = -5
so when y = 15, then x = -5

Answer 7

any questions ?

Answer 8

This is a new way to look at it :)

Answer 9

I just find it easier. But you have to set it up differently if it is an varies indirectly

Answer 10

that actually made more sense to me thanks c:

Answer 11

Usually I solve it in this manner:\[y=kx\]\[k=\frac{y}{x}~,~x=-2~,~y=6 ~,~\therefore k=\frac{6}{-2}=-3\]\[x=\frac{y}{k}~,~ y=15 \implies x=\frac{15}{-3} =~? \]

Answer 12

true...there is that way as well. Probably should learn it that way because the way I do it, you have to set it up differently if it varies indirectly

Answer 13

Ohh, how would you set it up if it varied indirectly? I'd like to see your method :D

Answer 14

I mean inversely*

Answer 15

I get confused on that...but I believe you set it up as an indirect proportion

Answer 16

Oh, hm, I see, I see.

Answer 17

I don't really know why I like this way better...I guess I am just kinda weird...lol

Answer 18

Nah :) everyone learns differently! I was only asking because I was genuinely curious to see /learn new methods of solving these types of problems :)

Answer 19

thats cool...I hope I helped some. Sorry about the varying indirectly...like I said, that confuses me a little