Question 989715
a.It means that Cost is a function of r in percent and since it involves money,it's unit depends on the contry to which it is being used.e.g if used in USA,the unit is dollar($).if used in Nigeria,the unit is naira(#).etc.
2.The statement f'(10)=1200
means that when the function is differentiated and 10 is logged into the drivative then the result will be 1200.
3.Since it involves money,The sign is always positive not nagative.even if there is nagative answer,take the modulus so as to get positive value.