Question

If y varies inversely as x and y = 12 when x = 3, find x when y = 18

Answer 1

Since, y varies inversely as x
hence \[\huge y \alpha \frac{1}{x} \rightarrow y = \frac{k}{x} \rightarrow y x = k\] where K is any constant. Let us find the value of constant K
So at y = 12 when x = 3
12 * 3= = k
i.e. k= 36
hence yx = 36 is the required eq of variation
Now at y = 18, x=?
Substituting y= 18 in eq of variation we find;
18* x= 36
x= 36/18
i.e. x= 2 is the required answer.
@grayp