1.{x/2+y/3=2x/3-y/4=72.2x-3y+4z=113x+4y-2z=103x-y-5z=-172.{2x-3y+4z=113x+4y-2z=103x-y-5z=-17

Question

1.{x/2+y/3=2 x/3-y/4=7 2.2x-3y+4z=11 3x+4y-2z=10 3x-y-5z=-17
2.{2x-3y+4z=11 3x+4y-2z=10 3x-y-5z=-17

Answer 1

x/2+y/3=2 ①
x/3-y/4=7 ②
①*2..③
②*3..④
④-③得.解出来是x或y,把它代入③或④.
2x-3y+4z=11 ①
3x+4y-2z=10 ②
3x-y-5z=-17③
①*3-②*2得.
再算③,解出来是x或y,把它代入③或④.