設直線L的斜率為3且X截距為2，下列何哪一點在直線L上? A(-1,-3) B(-1,3) C(1,3) D(1,-3)?

y=mx+c
代m=3,(x,y)=(2,0)
0=3(2)+c
c=-6
y=3x-6
3x-y-6=0
代A(-1,-3)=-6(delete)
代B(-1,3)=-12(delete)
代C(1,3)=-6(delete)
代D(1,-3)=0 ans