设y1=k1x,y2=k2(x-2)
由y=3y1-3y2
=3k1x-3k2(x-2)
(1)将x=1,y=-1代入:
-1=3k1+3k2
(2)将x=3,y=13代入:
13=9k1-3k2
(1)+(2)得k1=1,k2=-4/3,
∴y=3x+4(x-2)
=7x-8
设y1=k1x,y2=k2(x-2)
由y=3y1-3y2
=3k1x-3k2(x-2)
(1)将x=1,y=-1代入:
-1=3k1+3k2
(2)将x=3,y=13代入:
13=9k1-3k2
(1)+(2)得k1=1,k2=-4/3,
∴y=3x+4(x-2)
=7x-8