2X+5Y-13Z=1000 ;3X+3Z=9Y; 6Y+8Z-5X=-600
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2X+5Y-13Z=1000 ;3X+3Z=9Y; 6Y+8Z-5X=-600
详细解题说明!
详细解题说明!
2X+5Y=13Z-1000 ①
3X+3Z=9Y ②
6Y+8Z=5X+600 ③
②乘2/3
得2X+2Z=6Y ④
把④代入③
得2x+2z+8z=5x+600
10z=3x+600⑤
①乘9
18x+45y=117z-9000⑥
②乘5
15X+15Z=45Y
15X-45Y=-15Z ⑦
⑥+⑦
得33X=102Z-9000⑧
⑤乘11
得110Z=33X+6600⑨
⑧+⑨
110Z=102Z-2400
Z=-300
把Z=-300代入⑨
得-33000=33X+6600
-39600=33X
X=-1200
把Z=-300,X=-1200代入②
得9Y=-4500
Y=-500
得原方程组的解为{X=-1200 Y=-500 Z=-300
3X+3Z=9Y ②
6Y+8Z=5X+600 ③
②乘2/3
得2X+2Z=6Y ④
把④代入③
得2x+2z+8z=5x+600
10z=3x+600⑤
①乘9
18x+45y=117z-9000⑥
②乘5
15X+15Z=45Y
15X-45Y=-15Z ⑦
⑥+⑦
得33X=102Z-9000⑧
⑤乘11
得110Z=33X+6600⑨
⑧+⑨
110Z=102Z-2400
Z=-300
把Z=-300代入⑨
得-33000=33X+6600
-39600=33X
X=-1200
把Z=-300,X=-1200代入②
得9Y=-4500
Y=-500
得原方程组的解为{X=-1200 Y=-500 Z=-300
{2x+5y=13z+1000 {3x+3z=9y {6y+8z+600=5x
2X+5Y-13Z=1000 ;3X+3Z=9Y; 6Y+8Z-5X=-600
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
{x+y+z=1;x+3y+7z=-1;z+5y+8z=-2
x/10 = y/8 =z/9 求x+2y+3z/y-5z
试证明(x+y-2z)+(y+z-2x)+(z+x-2y)=3(x+y-2z)(y+z-2x)(z+x-2y)
(4x-2y-z)-{5x[8y-2y-(x+y)]-x+(3y-10z)]=? kuai
{2x+3y-4z=-5 x+y+z=6 x-y+3z=10
解方程组:x+y+z=4,x+y+2z=5,3x+y-z=6
2x+5y+4z=6,3x+y-7z=-4,x+y-z=?
5x+3y+2z=2011 4x+6y+7z=2012 求x+y+z