(y-c+3)²+2(c-y-3)(y+c+3)+(y+c+3)² = (y-c+3)²-2(y-с+3)(y+c+3)+(y+c+3)²

(y-c+3-(y+c+3))² = (y-c+3-y-c-3)² = (-2c)²

Подставим значения: (-2с)² =  (-2*0.2)² = (-0.4)² =0.16