１．
100 N=3
110 DIM A(N,N+1)
120 '
130 FOR J=1 TO N: FOR K=1 TO N+1: READ A(J,K): NEXT K: NEXT J
140 FOR J=1 TO N: FOR K=1 TO N+1: PRINT A(J,K);:NEXT K: PRINT: NEXT J:PRINT
150 '
160 FOR I=1 TO N
170 T = A(I,I): FOR K=1 TO N+1: A(I,K) = A(I,K) / T: NEXT K
180 FOR J=1 TO N
190 IF J<>I THEN T = A(J,I): FOR K=1 TO N+1: A(J,K) = A(J,K) - T*A(I,K):NEXT K
200 NEXT J
210 FOR J=1 TO N: FOR K=1 TO N+1: PRINT A(J,K);:NEXT K: PRINT: NEXT J:PRINT
220 NEXT I
230 '
240 FOR I=1 TO N: PRINT A(I,N+1): NEXT I
250 '
260 DATA 2, 1, 1, 2
270 DATA 2, 3, 1, 4
280 DATA 1, 1, 3, -1

２．
100 N=3 → N=6