Question

已知直线L1;Y=2X,过点A(2,-1)作直线L2交Y轴于C,交L1于B,且向量AB=2倍的向量BC,求L2方程

Answer 1

B(x,2x),C(0,y)

AB=(x-2,2x+1)

BC=(-x,y-2x)

AB=2BC

(x-2,2x+1)=2(-x,y-2x)

x-2=-2x

2x+1=y-2x

x=2/3

y=11/3

B(2/3,4/3),C(0,11/3)

y+1=-7/3(x-2)