横坐标:(取极限)x=1-4/9+16/81+(-4/9)^3+(-4/9)^4+…=1×[1-(-4/9)^n]/(1+4/9)=9/13
纵坐标:(取极限)y=2/3+(2/3)(-4/9)+(2/3)(-4/9)^2+(2/3)(-4/9)^3+…=(2/3)×[1-(-4/9)^n]/(1+4/9)=6/13
横坐标:(取极限)x=1-4/9+16/81+(-4/9)^3+(-4/9)^4+…=1×[1-(-4/9)^n]/(1+4/9)=9/13
纵坐标:(取极限)y=2/3+(2/3)(-4/9)+(2/3)(-4/9)^2+(2/3)(-4/9)^3+…=(2/3)×[1-(-4/9)^n]/(1+4/9)=6/13