Final answer:
To find dy when y=100 given x and dx, an equation linking x and y is needed. Without it, we can't calculate dy. The context implies a use of differential equations in a physical scenario.
Step-by-step explanation:
To find dy when y=100, given x and dx, we need to have a relationship between x and y, typically provided by an equation or a system of equations. Without this information, we cannot calculate the specific value of dy. However, based on the context of the information provided, it seems that we're dealing with a physical scenario possibly related to motion or forces where dy represents a small change in position (y coordinate) and dx represents a small change in another position (x coordinate).
The references to ady, udv, and variable separation suggest an application of differential equations to physical laws, perhaps dealing with kinematics or dynamics. The precise calculation of dy would depend on understanding the relationship between x and y, and then using differentiation, substitution, and integration to find the solution.