2,5a(a-2y)-2y(y-2,5a) при a = - 0,2, y = -0,5

2.5*(-0.2)*(-0.2-2(-0.5))-2*(-0.2)*(-0.5-2.5*(-0.2))-0.5*(-0.2+1)+0.4*(-0.5+0,5)-0.5*0.8+0.4*0-0.4+0=-0.4