Question

If y =12 when x= 6, find x when y=-24

Answer 1

find a point in a graph?

Answer 2

You would tell whoever gave this question that there isn't enough info.

Answer 3

does y vary directly with x maybe?

Answer 4

does y vary indirectly with x?
or you not given anything else?

Answer 5

yes, i want to know too..

Answer 6

Write an inverse variation equation that relates x and y. Assume that y varies inversely as x. Then solve.

Answer 7

\[y=\frac{k}{x}\]

Answer 8

plug in x=6,y=12 to find the constant k

Answer 9

that is the first step
then there is another step afterwards

Answer 10

simplify and substitute

Answer 11

okay i plugged everything in..

Answer 12

did you find the constant k?

Answer 13

that was the whole point in pluggin in your first part (x,y)=(6,12)

Answer 14

first pair*

Answer 15

so it'd be -3 ?

Answer 16

the answer is -12?

Answer 17

y=kx
12=k(6)
2=k
y=2x
-24=2x
x=-24/2
x=-12

Answer 18

I think 6(12) isn't -3

Answer 19

thats not even a choice.

Answer 20

\[y=\frac{k}{x} \\ xy=k \\ 6(12) =k\]

Answer 21

do you know how to multiply 6 and 12?

Answer 22

if you don't you can think of it as
12+12+12+12+12+12 (the sum of six 12's)

Answer 23

yes i do thanks but my teacher checked it and she said its right

Answer 24

oh you already did the question?

Answer 25

i did what you said to start off with but then she emailed me back and set it up

Answer 26

ok so when you said -3
you weren't talking about k
you were talking about the for x when y=-24

Answer 27

yes

Answer 28

\[xy=k \\ 6(12)=k \\ 72=k \\ \text{ yeah } k \text{ is 72} \\ xy=72 \text{ replaced } k \text{ with } 72 \\ \\ \text{ now what is } x \text{ when } y=-24 \\ -24x=72 \]
yep final answer is x=-3 when y=-24