Mrs. Gnanaharan is an OCT certified secondary math teacher with degree in mathematics as well as 12 years of teaching experience.  read more


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April 7, 2016

MCV4U (Calculus & Vectors):

How do I solve Derivative Application problems?

Type 1: Minimum and Maximum problems

Examples: greatest profit, least cost, least time, greatest voltage, optimum size, least size, greatest strength, and greatest distance.


1) When feasible, draw a diagram.

2) Define variables to the given quantities and quantities to be determined.

3) Write a primary equation for the quantity that to be maximized or minimized.

4) write a secondary equation for the given quantity.

5) Solve for one of the variables from the secondary equation.

6) Substitute into the primary equation so that primary equation has only one variable.

7) Determine the restrictions of the primary equation (domain). That is, determine which value make sense for the given problem.

8) Find the derivative of the NEW primary equation, set it equal to 0 and solve for the variable. We know maximum/minimum occur when derivative is zero.

9) Solve for other variable using the secondary equation.

10) Confirm if it is max/min by doing the second derivative test or first derivative test. If y''(c) >0, it is a min; If y ''(c) <0, it is a max; If y'' (c) = 0, test fails. In this case, use the first derivative test. Note that c is the critical number from the first derivative y ' = 0.

Stay tuned for Type 2: Related Rates.....

By Mrs. Uma Gnanaharan




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