x+2y=3a(2)
(2)-(1):
3y=3a-1
y=a-1/3
x=y+1=a+2/3
x>0,y<0
a+2/3>0
a-1/3<0
-2/3
方程组：x-y=1,x+2y=3a的解满足:x>0,y
方程组：x-y=1,x+2y=3a的解满足:x>0,y<0,则a的取值范围是?
数学人气：279 ℃时间：2020-09-10 17:52:37
优质解答
x-y=1(1)
x+2y=3a(2)
(2)-(1):
3y=3a-1
y=a-1/3
x=y+1=a+2/3
x>0,y<0
a+2/3>0
a-1/3<0
-2/3
x+2y=3a(2)
(2)-(1):
3y=3a-1
y=a-1/3
x=y+1=a+2/3
x>0,y<0
a+2/3>0
a-1/3<0
-2/3
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