z=x+iy i x,y∊R
|x+iy+i|+|x+iy−i|=4
|x+(y+1)i|+|x+(y+1)i|=4⇔
√x2+(y+1)2+√x2+(y−1)2=4
√x2+(y+1)2=4−√x2+(y−1)2 /2
x2+y2+2y+1=16−8√x2+y2−2y+1+x2+y2−2y+1
4y=16−8√x2+y2−2y+1 /:4
y=4−2√x2+y2−2y+1
2√x2+y2−2y+1=4−y /2
4(x2+y2−2y+1)=16−8y+y2
4x2+4y2−8y+4=16−8y+y2
4x2+3y2=12 /:12
| x2 | y2 | ||
+ | =1 ⇔ | ||
| 3 | 4 |
| x2 | y2 | ||
+ | =1 elipsa | ||
| (√3)2 | 22 |