解聯立方程式~數學教教我~

1.{3x y=3{2x 2y=-222.{3x=4y{x=2y-43.{2x 3y=-4{-3x 2y=194.{4x 2y=2700{3x 1y=18505.{x y/10=361{x 10y 1=2837
1.將第1式*26X 2Y=6 第3式第3-2式 4X=28x=7 帶回第1式21 Y=3Y=3-21 Y=-18
1.(3X Y=3)x2 ...=6X 2Y=6 //解方程式 (6X 2Y=6)-(2X 2Y=-22) ....4X=28 X=7X=7帶入3X Y=3...Y=-182.將X=2Y-4帶入3X=4Y.....3(2Y-4)=4Y......6Y-12=4Y.....2Y=12....Y=6Y=6帶回3X=4Y...3X=4x6=24.....X=83.3(2X 3Y=-4) 2(-3X 2Y=19)........(6X 9Y=-12) (-6X 4Y=38).....13Y=26...Y=2Y=2帶回2X 3Y=-4.....2X 6=-4...2X=-10....X=-54.(4X 2Y=2700)-(3X Y=1850)......X Y=850.....用(3X Y=1850)-(X Y=850)...2X=1000...X=500帶入X Y=850.....Y=3505.10(X Y/10=361) (X 10Y 1=2837)....(10X Y=3610) (X 10Y=2836)....11X 11Y=6446...X Y=586...(X 10Y=2836)-(X Y=586)...9Y=2250...Y=250Y=250帶入X Y=586...X=336
1.{ y=3-3x ------1式{ x y=11 -------2式1式代入2式x 3-3x=11-2x=8x=-4 代回1式y=3-(-12)y=152.{3x=4y ------1式{x=2y-4 ------2式2式代入1式6y-12=4y2y=12y=6 代回2式x=12-4x=83.{2x 3y=-4 ------1式 =