Y1=K1X
Y2=K2(X-1)
Y=Y1+Y2=K1X+K2(X-1)=(K1+K2)X-K2
当x=2时,y=10,当x=3时,y=9
10=(K1+K2)*2-K2
9=(K1+K2)*3-K2
K1=11,K2=-12
Y=-X+12