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Cod
Mar2-04, 02:27 AM
Here's the equation:

F(x) = (x-1)(x-2)(x-3)


I know how to diff. using the product rule when you only have 2 equations, but not 3.I looked at the examples in my book and none of them show how you would work out this sort of problem. So if someone could give me the basic overview of how to differentiate a problem like this, I'd greatly appreciate it.

Cod
Mar2-04, 02:32 AM
Could I change the equation to read like this before diff. it:

F(x) = (x-1)(x^2-5x+6) ???



Then I could just use the product rule from there.

himanshu121
Mar2-04, 04:30 AM
consider u,v,w as a function of x

then \frac{d}{dx}uvw = uv \frac{d}{dx}w + vw\frac{d}{dx}u + uw\frac{d}{dx}v

ShawnD
Mar2-04, 05:05 AM
Just expand it then differentiate. According to Maple, you get the same answer.


Here is when you differentiate 3 terms

> R3 := diff((x-1)*(x-2)*(x-3),x);

R3 := (x - 2) (x - 3) + (x - 1) (x - 3) + (x - 1) (x - 2)

> R4 := expand(R3);
R4 := 3 x^2 - 12 x + 11


Here is when you expand it then differentiate it

R1 := expand((x-1)*(x-2)*(x-3));
R1 := x^3 - 6 x^2 + 11 x - 6

> R2 := diff(R1,x);
R2 := 3 x^2 - 12 x + 11



You end with the same answer. Just expand it; it's much easier.