# Does anyone have a good site for step by step calc help?

#### CraKaJaX

##### Lifer
The calc book that we use is absolute crap. The chapter dealing with implicit differentiation is so confusing I have no idea where numbers or variables come from. Anyone recommend a helpful site that you have used or know of? Or better yet.. can anyone here give me the basic rules or something? Yes, I googled it. The sites that come up are just as confusing.

HS or Uni?

#### FleshLight

##### Diamond Member
It's basically dy/dx = f(x) and doing algebraic manipulation.

So if you have -2x + y = 6
y = 2x + 6

dy/dx = 2

#### blackllotus

##### Golden Member
Have you done partial derivatives yet?

#### CraKaJaX

##### Lifer
Originally posted by: blackllotus
Have you done partial derivatives yet?
Yes, but... in physics. And the calc test is not covering it. I understand everything that's going to be on the test EXCEPT this chapter. :|

#### imported_quasi

##### Member
Originally posted by: FleshLight
It's basically dy/dx = f(x) and doing algebraic manipulation.

So if you have -2x + y = 6
y = 2x + 6

dy/dx = 2
Implicit derivation is not meant for problems where the y variable can be easily isolated.

For implicit derivation, you essentially need to take the derivative of each value (with respect to x).

For the equation x^4 + 2y^2 = 8:
dy/dx[x^4] = 4x^3
dy/dx[2y^2]= 4y * dy/dx, using the chain rule on y and multiplying by the derivative of y at the end
dy/dx = 0

4x^3 + 4y * dy/dx = 0
4y * dy/dx = -4x^3
dy/dx = -4x^3 / 4y
dy/dx = -x^3 / y