Y varies inversely as twice x when x=9, y=2, find y when x=3? can someone work this out for me and then explain how they did it?

Question

lgbasallote · Answer

do you know the equation for inverse variation?

anonymous · Answer

no this was all i was given...:/

lgbasallote · Answer

it's never given...it's memorized...

anyway the equation for the inverse variation is $$y = \frac kx$$
okay?

anonymous · Answer

okay yes got that...

lgbasallote · Answer

good. here, it says y varies inversely as TWICE x so your equation would be $$y = \frac k{2x}$$
follow so far?

anonymous · Answer

yes i follow

lgbasallote · Answer

now it says x=9 when y = 2

so substitute x = 9 and y = 2 into $$y = \frac k{2x}$$
then solve for k

anonymous · Answer

so now it would be 2= k/2(2)   Right now i solve for k

lgbasallote · Answer

no

2 = k/2(9)

anonymous · Answer

oppies my bad

lgbasallote · Answer

now solve for k

anonymous · Answer

okay so i have 2=k/2(9)

now i multiply 2(9)=18 then divide by 2 and k =9

2=k/18
k=9

anonymous · Answer

i thinkk???

anonymous · Answer

right ??  @igbasallote

lgbasallote · Answer

you don't divide by 2..you multiply both sides by 18