Re: Simplyfying expression
- To: mathgroup at smc.vnet.net
- Subject: [mg30632] Re: [mg30624] Simplyfying expression
- From: BobHanlon at aol.com
- Date: Fri, 31 Aug 2001 19:58:09 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
In a message dated 2001/8/31 4:23:48 AM,
shusaku.yamamoto at buseco.monash.edu.au writes:
>I have another problem. I tried simplifying the solutions of a
>simultaneous difference equations; i.e. I typed
>
>Simplify[-1-5*(3^x)+(31/63)*(2^(2+x))*(5^(1+x))-((53*(10^x))/63)]
>Simplify[-1-5*(3^x)+(31/63)*(2^(2+x))*(5^(1+x))-((53*(10^x))/63),x "set
>of" Reals]
>FullSimplify[-1-5*(3^x)+(31/63)*(2^(2+x))*(5^(1+x))-((53*(10^x))/63)]
>
>Yet, Mathematica does not simplify the expressions. I know the above
>expression can be written as:
>-1-5*(3^x)+9(10^x).
>
expr=-1-5*3^x+(31/63)*2^(2+x)*5^(1+x)-(53*10^x)/63;
Using brute force
FullSimplify[expr /.
2^x_ -> a*2^(x-1 )] /.
a -> 2
-1 - 5*3^x + 9*10^x
Bob Hanlon
Chantilly, VA USA