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

CraKaJaX

Lifer
Dec 26, 2004
11,905
148
101
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.
 

FleshLight

Diamond Member
Mar 18, 2004
6,883
0
71
It's basically dy/dx = f(x) and doing algebraic manipulation.

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

dy/dx = 2
 

CraKaJaX

Lifer
Dec 26, 2004
11,905
148
101
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. :|
 
Mar 8, 2005
126
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0
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[8] = 0

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

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