Question

inverse variation help

1.suppose that y varies inversely with x, and y=6 when x=8. what is an equation for the inverse variation?

2.suppose that y varies inversely with x, and y=0.2 when x=2. what is an equation for the inverse variation?

Answer 1

1. options
y=x/48
y=2x
x=y/2
y=48/x

2.options

y=1.8x
y=0.4/x
x=y/1.8
y=x/0.4

Answer 2

do you know what "y varies inversely with x" means?

Answer 3

i know what inverse is but no I'm not sure

Answer 4

then i will tell you
it means there is some number, usually denoted by \(k\) but it is just some number, where
\[\huge y=\frac{k}{x}\] and your job is to find that \(k\)

Answer 5

take the expression \(\huge y=\frac{k}{x}\)
where you see a \(y\) put \(6\)
where you see an \(x\) put \(8\)
you will have a simple equation to solve for \(k\)

Answer 6

okay hold on

Answer 7

i am holding...

Answer 8

i got 48

Answer 9

so 48/x is the correct answer?

Answer 10

me too

Answer 11

yeah
\[y=\frac{48}{x}\]

Answer 12

and 2 is .4/x :)

Answer 13

yep

Answer 14

okay so 2 more questions or 1 really how do i find out if a table represents a direct variation or inverse

Answer 15

whats the whole question

Answer 16

NICE WORK

Answer 17

and what that variation is

Answer 18

it is nice when someone actually tries something rather than repeatedly asking the same questions

Answer 19

thank you for helping me(:

okay this is a table
x:2,4,6,8
7:14,28,42,56

Answer 20

you have to look at two points on the table or graph

Answer 21

that is your table, it is pretty clear that as x gets bigger, so does y, so it COULD be direct variation

Answer 22

you can check it by checking to see if the first number, the x, is multiplied by the same number each time to get the y

Answer 23

everything is times 7 isnt that the direct varition

Answer 24

i think its direct and y=7x?

Answer 25

yea

Answer 26

haha you typed that before me

Answer 27

you can usually do it in your head, as in this case
if it is not obvious check \(\frac{y}{x}\) and see if you keep getting the same number

Answer 28

if, as x gets bigger, y gets smaller it MAY be inverse variation or whatever they call it

Answer 29

I'm looking at this one and its not as easy

x:2,4,8,12
y:4,2,1,2/3

Answer 30

it is always possible the answer is NO

Answer 31

so this is inverse because the y gets smaller

Answer 32

here as x gets bigger y gets smaller so check to see if the product of the two numbers is always the same

Answer 33

yea right
and what do you get when you multiply each pair of numbers?

Answer 34

8

Answer 35

you should see that in fact this is even easier than checking direct variation
right
easy yes?

Answer 36

:D

Answer 37

so you know what it looks like as an equation right?

Answer 38

yes thank you so much

Answer 39

yw