七下数学书习题8.4,1题2题答案
1.(1){y=2x-7,5x+3y+2z=2,3x-4z=4
(2){4x+9y=12,3y-2z=1,7x+5z=4分之19
2.(1){4x-9z=17,3x+y+15z=18,x+2y+3z=2
(2){2x+4y+3y=9,3x-2y+5z=11,5x-6y+7z=13