THE EQUATION OF NORMAL AT ? ON THE ELLIPSE x²/a²+y²/b²=1 IS ax/cos?-by/sin?=a²-b².IF THE NORMALS AT ?_r (r=1,2,3) ON THE ELLIPSE ARE CONCURRENT AT

(h,k) AND IF z=cos?_r+isin?_{r ,}THEN (a²-b²)z⁴-2(ah-bk)z³+2(ah+ibk)z-(a²-b²) IS EQUAL TO WHAT???

0 by property no. 5 of complex numbers and modulus of complex numbers

C'MON SOMEBODY ANSWER