Re: Why isn't Expand grouping terms by order?
- To: mathgroup at smc.vnet.net
- Subject: [mg87892] Re: Why isn't Expand grouping terms by order?
- From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
- Date: Sat, 19 Apr 2008 03:37:03 -0400 (EDT)
- Organization: The Open University, Milton Keynes, UK
- References: <firstname.lastname@example.org>
p at dirac.org wrote: > Consider this: > > In:= Expand[ (1+a*x)*(1+b*x), x] > > 2 > Out= 1 + a x + b x + a b x > > > How can I coax Mathematica to give me this, instead: > > 2 > Want= 1 + (a + b) x + a b x > > Why isn't Mathematica reporting the answer in terms of powers of x? The function *Collect* is what you are looking for. In:= Collect[(1 + a*x)*(1 + b*x), x] Out= 1 + (a + b) x + a b x^2 In:= Expand[(1 + a*x)*(1 + b*x), x] Out= 1 + a x + b x + a b x^2 In:= Collect[%, x] Out= 1 + (a + b) x + a b x^2 Regards, -- Jean-Marc