a,b,c,d = var ('a,b,c,d')
solve([a+b+c*0+d*0 ==0 ,a+b*0+c*0+d == 0,a*0+d*0+b+c == 0,a*0+b*0+c+d == 1],a,b,c,d)

Kreyszig-2.3-13 (last edited 2010-12-17 05:38:11 by harsha)