If g varies inversely as the square root of h, this means that the product of g and the square root of h is constant. We can represent this relationship using the equation g*sqrt(h) = k, where k is the constant value.
We are given that g = 9 when h = 121, so we can substitute these values into the equation to find the constant:
9sqrt(121) = k
Simplifying this expression gives us:
k = 911 = 99
Now that we know the value of the constant, we can use the equation to find g when h = 81:
g*sqrt(81) = 99
Solving for g gives us:
g = 99/sqrt(81) = 99/9 = 11
Therefore, when h = 81, g = 11.