Re : Simplify

*To*: mathgroup at smc.vnet.net*Subject*: [mg14866] Re : [mg14780] Simplify*From*: POITEVINEAU Yvon <ypoit at lac2.gulliver.fr>*Date*: Mon, 23 Nov 1998 10:11:47 -0500*Sender*: owner-wri-mathgroup at wolfram.com

Jurgen Tischer wrote : >Subject: [mg14866] [mg14780] Simplify > >Could someone tell me please how to simplify the following formula? > >(-7253*2^(1 + 2*n)*5^n - 523*4^n*5^(1 + n) + 17121*20^n + > 130321*20^n*n^4)/130321 > >To my surprise when I changed by hand (with two rules) the powers of 2, >5 and so on to powers of 20, Mathematica changed them back to this >form. Try this : In[1]:= expr=(-7253*2^(1 + 2*n)*5^n - 523*4^n*5^(1 + n) + 17121*20^n + 130321*20^n*n^4)/130321; expr/20^n // Expand Out[1]= n^4 --- Yvon Poitevineau