> cc<-c(1,2,3,4,5,2,1,2,3,4,3,2,1,2,3,4,3,2,1,2,5,4,3,2,1)
> A<-matrix(cc,5,5)
> A
     [,1] [,2] [,3] [,4] [,5]
[1,]    1    2    3    4    5
[2,]    2    1    2    3    4
[3,]    3    2    1    2    3
[4,]    4    3    2    1    2
[5,]    5    4    3    2    1
> b<-matrix(c(7,-1,-3,5,17),5,1)
> b
     [,1]
[1,]    7
[2,]   -1
[3,]   -3
[4,]    5
[5,]   17
> x<-solve(A)%*%b
> x
     [,1]
[1,]   -2
[2,]    3
[3,]    5
[4,]    2
[5,]   -4