posted by evelyn .
same question, but it didn't come across right.
500 equals 1 over X to the half
500 = 1/(X^1/2)
Multiply both sides by X^1/2.
500*X^1/2 = (1*X^1/2)/X^1/2.
X^1/2 divides out on the right side leaving
500*X^1/2 = 1.
Now square both sides.
[500*X^1/2]^2 = 1.
250*10^3*X = 1
Then solve for X. I will let you take it from here. I hope this helps.