Question

If y varies inversely as x, and y = 18 when x = 2, how do you find y when x = 4?

Answer 1

y = 9

Explanation:

If x is doubled then y is cut in half, since they are inversely related

`18/2 =9`

Answer 2

`y=9`

Explanation:

`"the initial statement is "yprop1/x`

`"to convert to an equation multiply by k the constant"`
`"of variation"`

`rArry=kxx1/x=k/x`

`"to find k use the given condition"`

`y=18" when "x=2`

`y=k/xrArrk=yx=18xx2=36`

`"equation is " color(red)(bar(ul(|color(white)(2/2)color(black)(y=36/x)color(white)(2/2)|)))`

`"when "x=4" then"`

`y=36/4=9`