Question

已知关于x,y的方程组2x-y=2a,x+3y=a-1的解满足x>y,求a的取值范围

一定要步骤，谢谢大家了

Answer 1

2x-y=2a,(1)
x+3y=a-1 (2)
(1) * 3得
6x - 3y = 6a (3)
(2)+(3)得
7x = 7a -1
x = a - 1/7
代入（1）得
y = -2/7

又 x > y
a - 1/7 > - 2/7
a > - 1/7

Answer 2

x+3y=a-1
x=a-1-3y
2a-2-6y-y=2a
-2-6y-y=0
y= -2/7
x=(a-1)/7
x>y,
(a-1)/7> -2/7
a>-1

Answer 3

2x-y=2a x+3y=a-1
解方程组得 x=(7a-1)/7
y= -2/7
x>y 7a -1> -2
a>-1/7