1.2x+3y=7 ……………………………………………………①
y=5x-9……………………………………………………… ②
②代入①,得
2x+3(5x-9)=7
解得,x=2
代入②解得,y=1
依题意,把x=2,y=1 代入方程3x+my=8,解得 m = 2
2.原方程组转化为
y= x + 5/12…………………………………………①
2x-3y=1……………………………………………②
①代入②,得
2x - 3(x+5/12) =1
化简解得,x = - 9/4
把x = - 9/4代入①,解得 y= - 11/6