1.由5(x-3y)-6=2x+1 得3x-15y=7 (1)
由3(x+6y)+4=9y+19 得3x+9y=15 (2)
x=4
y=1/3
2.由x+2y=9 (1) 5z-x=14 (3) (1)+(3)得2y+5z=23 代入y-3z=-5
得x=1,y=4,z=3
3.(1)+(2)得4x+3y=1,(1)*2+(3)得5x+7y=1
x=4/13,y=-1/13,z=-6/13.
4.三个方程相同,都是4a+2b+c=3,怎么求?
请教几道二元和三元一次方程组的题目,
1.由5(x-3y)-6=2x+1 得3x-15y=7 (1)
由3(x+6y)+4=9y+19 得3x+9y=15 (2)
x=4
y=1/3
2.由x+2y=9 (1) 5z-x=14 (3) (1)+(3)得2y+5z=23 代入y-3z=-5
得x=1,y=4,z=3
3.(1)+(2)得4x+3y=1,(1)*2+(3)得5x+7y=1
x=4/13,y=-1/13,z=-6/13.
4.三个方程相同,都是4a+2b+c=3,怎么求?