Question

If y varies inversely as x and y = 20 when x = 10, then how do you find the constant of the variation?

Answer 1

constant of variation: `200`

Explanation:

If `color(red)(y)` varies inversely as `color(blue)(x)` then
`color(white)("XXX")x*y=c` for some constant of variation `c`

Given `color(red)(y)=color(red)(20)` when `color(blue)(x)=color(blue)(10)` is a solution to this equation
then
`color(white)("XXX")color(blue)(10)*color(red)(20) = c`

`rArr c= color(green)(200)`