Question about Collect
- To: mathgroup at smc.vnet.net
- Subject: [mg71273] Question about Collect
- From: "dimitris" <dimmechan at yahoo.com>
- Date: Sun, 12 Nov 2006 06:48:51 -0500 (EST)
Consider the following simple expression
expr = Collect[x^3 - c*x^2 - 3*a*x - b /. x -> y + c/3, y]
-b - a*c - (2*c^3)/27 + (-3*a - c^2/3)*y + y^3
I can't understand the difference between the two outputs below
expr /. {-b - a*c - (2*c^3)/27 -> A1, -3*a - c^2/3 -> A2}
A1 + (-3*a - c^2/3)*y + y^3
(*and*)
expr /. -b - a*c - (2*c^3)/27 -> A1 /. -3*a - c^2/3 -> A2
A1 + A2*y + y^3
I waited to be the same.
Any guidance/insight?
Dimitris