方程①\(xy = 1\)②\(y = 3x - 1\)③\(x + \frac{1}{y} = 2\)④\(x + y + z = 1\)-可可试卷app

“微信扫一扫”进入"可可试卷"微信小程序刷题

方程①\(xy = 1\)②\(y = 3x - 1\)③\(x + \frac{1}{y} = 2\)④\(x + y + z = 1\)中，是二元一次方程的有___

参考答案：②