Posting...#10

Calc was kind of hard for me this week we did implicit derivatives first ones and seconds ones…O.o and we also did Related rates implicit derivatives wasn’t really that hard but I have trouble with related rates in a few ways. I know the steps which are
1. Identify all variables and equations
2. Identify what you are looking for
3. Make a sketch and label
4. Write an equation involving your variables
5. Take the derivative with respect to time
6. Substitute in derivative and solve.
Now I know the steps of related rates but my biggest and I mean a big problem for me this is a problem for me in optimization too and that is step four. For related rates I don’t know how to find an equation or what equation to use for an example of a circle if you’re looking for area the equation would be: A= (pie)r^2 which I wouldn’t of know but should of and for optimization I still can’t find a primary and secondary I have to say this is my biggest problem in calculus.

Like for area and volume if you have a problem like 20(in our packet)
20. volume all edges of a cube are expanding at a rate of 3 centimeters per second. How fast is the volume changing when each edge is (a) 1 centimeter and (b) 10 centimeters?
I know how to draw the picture and tell my variables and what im looking for its just when I get to step 4 and have to make and equation.