Question

d(t)=750t/(t+12) where t is the age in years and d is the dosage. what is an expression for the rate of change of a child's dosage with respect to the child's age?

Answer 1

This just wants the derivative which you can solve for.
You can do this using a negative expononet or using ...the rational rule forget its name*.... you shoudl get 9000/(t+12)^2


*Quotient rule