Math Goodies is a free math help portal for students, teachers, and parents.
|
Interactive Math Goodies Software

testing left nav
Math Forums @ Math Goodies
Home | Profile | Active Topics | Members | Search | FAQ
 All Forums  Homework Help Forums  Pre-Calculus and Calculus  derivatives of trig New Topic  Reply to Topic  Printer Friendly
Author  Topic

effort
Senior Member

USA
38 Posts

 Posted - 10/17/2013 :  00:25:13 Find the derivative of sec(x).my work: (d/dx)sec(x)=sec(x)tan (x)(2x)My question is why is it that there should be only one 2x. According to the chain rule, I suppose to take the derivative of the inside function. Well, there are two x, so why do I not have to write 2x twice. i don't understand.Also how do you know which is the interior and exterior functions when finding trig derivatives? For example: find dy/dx of y = 4sin(3x)

Ultraglide

299 Posts

 Posted - 10/18/2013 :  17:24:09 When differentiating sec(x), you get sec(x)tan(x). Note that the arguements are both the same. When you apply the chain rule you apply it to the arguement of the secant (i.e. the orginal function), so you only do it once. When you start applying the chain rule, you start with the outer part and work your way 'inside'. In the example you used the sine is the outer and the 3x is the inner.
Topic
 New Topic  Reply to Topic  Printer Friendly Jump To: Select Forum New Visitor Forum       Testing Forum Homework Help Forums       Basic Math and Pre-Algebra       Algebra       Geometry and Trigonometry       Pre-Calculus and Calculus       Probability and Statistics       Standardized Test Preparation Help       Miscellaneous Math Topics Educator Forum       Teacher Talk Parent Forum       Parent's Place  -------------------- Home Active Topics Frequently Asked Questions Member Information Search Page
 Math Forums @ Math Goodies © 2000-2004 Snitz Communications