若Y1=-X+3,Y2=3X-4 ,试确定当X取何值时:(1)Y1小于Y2 (2)Y1等于Y2 (3)Y1大于Y2

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若Y1=-X+3,Y2=3X-4 ,试确定当X取何值时:(1)Y1小于Y2 (2)Y1等于Y2 (3)Y1大于Y2
若Y1=-X+3,Y2=3X-4 ,试确定当X取何值时:(1)Y1小于Y2 (2)Y1等于Y2 (3)Y1大于Y2

若Y1=-X+3,Y2=3X-4 ,试确定当X取何值时:(1)Y1小于Y2 (2)Y1等于Y2 (3)Y1大于Y2
(1)
-x+34+3
4x>7
x>7/4
当x>7/4 Y1小于Y2
(2)
-x+33x-4
x

(1)Y1即-X+3<3X-4
化简:-4X<-7
得X> 7/4
(2) Y1=Y2
即-X+3=3X-4
化简:-4X=-7
得X= 7/4
(3) Y1>Y2
即-X+3>3X-4
化简:-4X>-7
得X< 7/4