Question

Suppose that x=6 and y=8. If y is inversely related to x, what it y when x=3?

4
5
16
18

Answer 1

What *is not What it, I know how to do direct variation but i get confused with inverse relations, please if someone could explain this to me that would be awesome!

Answer 2

How do you do *direct variation* ?

Answer 3

Well direct variation has the form y=kx where k is not equal to zero

Answer 4

inverse variation is almost the same, except inverse means *divide* by x

y = k/x

Answer 5

Right how do i apply to this problem?

Answer 6

if you they give you a pair of numbers (and they do)
x=6 and y=8
replace x with 6 and y with 8 in

y = k/x

can you do that ?

Answer 7

8=k/6, okay where do i go from there? do plug in 3 for k?

Answer 8

next step is solve for k.
to do that you multiply both sides by 6
like this

8*6 = 6* k/6
the right side has 6*k/6 which can be written as k*6/6 (change the order of multiplying)
and then notice 6/6 is 1
you get
8*6= k
or
k= 48

once you found the "magic number" k , you use it by putting in the number in
y = k/x

in other words, your inverse variation equation is
y= 48/x

now if you are given an x (a new number) put that number in for x in the equation and simplify to find y

what is y when x is 3 ?

Answer 9

oh so then y=48/3 = 16!! so y is 16 when x is 3, that makes sense got it!! now i can solve the rest of these prob thanks!!!

Answer 10

these problems take 3 steps:
1) write down the equation
2) solve for k using the info they give you
3) use k in the equation, and use it to answer the question

Answer 11

Thanks a lot @phi !! ur a lot better at explaining then teacher or textbook!

Answer 12

yw