Re: why does it still running?!

*To*: mathgroup at smc.vnet.net*Subject*: [mg113164] Re: why does it still running?!*From*: István Zachar <zac at freemail.hu>*Date*: Sat, 16 Oct 2010 13:10:53 -0400 (EDT)*References*: <i9a4v4$nbd$1@smc.vnet.net>

On Oct 15, 8:02 pm, olfa <olfa.mra... at yahoo.fr> wrote: > Hi Mathematica community, > why Mathematica still running and so can't give me a solution for this sy= stem > Reduce[ > ((1 - a)*x - b)/a^(i/1) == ((1 - a)*y - b)/a^(j/1) && j == 10,{y}= , > Backsubstitution -> True] > > Thank you very much. On my machine (2 Intel CPU @ 2.4GHz, 2 GB RAM, Win 7, Mathematica 7.0.1.0) it produces the output immediately: In[1]:= Reduce[((1 - a)*x - b)/a^(i/1) == ((1 - a)*y - b)/a^(j/1) && j == 10, {y}, Backsubstitution -> True] Out[1]= (j == 10 && a == 1 && b == 0) || (j == 10 && (-1 = + a) a != 0 && y == -(( a^-i (-a^10 b + a^i b + a^10 x - a^11 x))/(-1 + a))) || (j == 10 && b != 0 && a == 1) Istvan