已知y1=-x+3,y2=3x-4,当x取何值时y1=y2?当x取何值时y1〉y2?当x取何值时y1〈y2?

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已知y1=-x+3,y2=3x-4,当x取何值时y1=y2?当x取何值时y1〉y2?当x取何值时y1〈y2?
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已知y1=-x+3,y2=3x-4,当x取何值时y1=y2?当x取何值时y1〉y2?当x取何值时y1〈y2?
已知y1=-x+3,y2=3x-4,当x取何值时y1=y2?当x取何值时y1〉y2?当x取何值时y1〈y2?

已知y1=-x+3,y2=3x-4,当x取何值时y1=y2?当x取何值时y1〉y2?当x取何值时y1〈y2?
当x取何值时y1=y2?
-x+3=3x-4
-x-3x=-4-3
-4x=-7
x=7/4
当x取何值时y1〉y2
-x+3>3x-4
-4x>-7
x<7/4
当x取何值时y1〈y2
-x+3<3x-4
-4x<-7
x>7/4

∵y1=y2
∴-x+3=3x-4
得x=7/4
∵y1<y2
∴-x+3<3x-4
得x>7/4
∵y1>y2
∴-x+3>3x-4
得x<7/4