KPQ=(1-0)/(-2+4)=1/2
KPR=(-1-1)/(2+2)=-1/2
KPQ+KPR=1/2-1/2=0
KRQ=(-1-0)/(2+4)=-1/6
过p点的切线斜率,kP=0+1/6=1/6
求过P点的椭圆切线方程y-1=(x+2)/6
6y-x-8=0
KPQ=(1-0)/(-2+4)=1/2
KPR=(-1-1)/(2+2)=-1/2
KPQ+KPR=1/2-1/2=0
KRQ=(-1-0)/(2+4)=-1/6
过p点的切线斜率,kP=0+1/6=1/6
求过P点的椭圆切线方程y-1=(x+2)/6
6y-x-8=0