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