The values of x and y are always positive, and x^2 and y vary inversely. If y is 10 when x is 2, then find x when y is 4000.

y ==1/x^2 * k, where k==constant of proportionality

10 ==1/2^2 * k, solve for k

10 ==1/4 * k

k ==40

4000 ==1/x^2 * 40

4000/40 ==1/x^2100 == 100 ==1/x^2, solve for x

x ==+or- 1/10