If y varies inversely with x, and y= 6 when x= 18, how do you find y when x= 8?

2 Answers
Binayaka C.
Jul 9, 2016

#y=13.5#

Explanation:

#y prop 1/x or y = k*1/x or x*y=k; y=6 ; x=18 :. 6*18=k or k=108# k= constant of variation. So the inverse variation equation is #x*y=108#
Now #x=8 :. 8*y=108 or y=108/8=13.5#[Ans]

Acquaintance
Jul 9, 2016

#y = 13/5#

Explanation:

Inverse variations look like this: #y = k/x#

We need to make our own inverse variation given #y=6# and #x=18#. We can plug this into the standard inverse variation with variables.

#y = k/x#

#6 = k/18#

#108 = k#

We've determined that #k=108#. Now we have what it takes to create an inverse variation. This is our final equation:

#y = 108/x#

We still need to find what #y# equals when #x# is #8#. Let's plug in #8# for #x#.

#y = 108/x#

#y = 108/8#

#y = 13.5#

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