1.3x+2y+z=13

来源：学生作业帮编辑：作业帮分类：数学作业时间：2024/09/13 12:14:08

1.3x+2y+z=13
x+y+2z=7
2x+3y-z=12
2.x+2y+3z=11
x-y+7z=10
x+3y+2z=2
3.若方程组4x+3y=1
ax+（a-1）y=3的解,x、y相等,则a的值为_______
A.4 B.10 C.11 D.12
请说出答案以及解题思路

1.3x+2y+z=13 ①
x+y+2z=7 ②
2x+3y-z=12 ③
①+③ 5x+5y=25 ④
①×2 6x+4y+2z=26 ⑤
⑤-② 5x+3y=19 ⑥
④-⑥ 2y=6 y=3 x=2 z=1
2.x+2y+3z=11 ①
x-y+7z=10 ②
x+3y+2z=2 ③
①-② 3y-4z=1 ④
①-③ -y+z=9 ⑤
得 y=-37 z=-28
X=169
3.若方程组4x+3y=1
ax+（a-1）y=3的解,x、y相等,则a的值为_B______
A.4 B.10 C.11 D.12
X=y x=y=1/7
代入下式得a=10

试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y) 2x+y+z=17 x+2z+y=14 x+z+2y=13 求:xyz 1.x+y+z=21,x-y=1,2x+z-y=13.2.3x+2y+z=13,x+y+2z=7 ,2z+3y-z=12 3x+2y+z=13 x+y+2z=7 2x+3y-z=12 x=?y=?z=? {3x+2y+z=13 x+y+2z=7 2x+3y-z=12,求x,y,z (x+y-z)^2-(x-y+z)^2=? 解一道三元一次方程x+y+z=13,y-2=z,100z+10y+x+99=100x+10z+y. x,y,z为实数且(y-z)^2+(x-y)^2+(z-x)^2=(y+z-2x)^2+(x+z-2y)^2+(x+y 分解因式:f(x,y,z)=x^2(y-z)+y^2(z-x)+z^2(x-y) x,y,z为实数且(y-z)平方+(x-y)平方+(z-x)平方=(y+z-2x)平方+(z+x-2y)平方+(x+y- x/2=y/3=z/5 x+3y-z/x-3y+z 2X+Y+Z=10,X+2Y+Z=-6,X+Y+2Z=8 5X+4Y-3Y=13,2X-3Y+7Z=19,3X-Y=2X