Svetlana K. answered 02/13/13
Math/Chemistry Tutor
check out this link:
http://education.ti.com/calculators/timathnspired/US/Activities/Detail?sa=5022&t=5025&id=11977
but in general lets say we consider linear function y1=ax+b and exponential y2=e^x
the rate of the function is its derivative:
y1'=a (constant rate) y2'=e^x (rate is getting bigger in time)