Question

If y varies inversely as x and y= 2/5 when x= 2, find y when x= 1

Answer 1

y = 4/5

Explanation:

Since, y varies inversely as x.

`\therefore \: y = (k)/(x) \\ (k = constant \: of \: proportionality) \\ \therefore \: xy = k...(1) \\ plug \: y = (2)/(5) \: and \: x = 2 \: in \: (1) \\ 2* (2)/(5) = k \\ \implies \: k = (4)/(5) \\ substituting \: k= (4)/(5) \: in \: (1) \\ xy = (4)/(5) ..(2) \\ this \: i s \: the \: equation \: of \: variation \\ plug \: x = 1 \: in \: (2) \\ 1 * y = (4)/(5) \\ \huge \red{ \boxed{y = (4)/(5) }}`