[Maxima] Chain Rule Question

Jaime Villate villate at fe.up.pt
Thu May 29 02:41:04 CDT 2008


On Wed, 2008-05-28 at 11:27 -0600, Ronald Modesitt wrote:
> Do you have some environmental constants set? I get an answer that is
> quite different.

Your problem was the use of braces { }. In Maxima, you must use regular
parenthesis for all grouping levels. The brackets and braces are
reserved for other purposes:

What you did:

(%i2) y(x):={(a*x+b)/(c*x+d)}^7$
(%i3) diff(y(x),x);
(%o3) 7*{(a*x+b)/(c*x+d)}^6*'diff({(a*x+b)/(c*x+d)},x,1)

what you should do:
(%i4) y(x):=((a*x+b)/(c*x+d))^7$
(%i5) diff(y(x),x);
(%o5) 7*a*(a*x+b)^6/(c*x+d)^7-7*c*(a*x+b)^7/(c*x+d)^8
(%i6) factor(%);
(%o6) 7*(a*d-b*c)*(a*x+b)^6/(c*x+d)^8

Regards,
Jaime



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