(x+2)²-4x(1-3x)=x²+4x+4-4x+12x²=13x²+4=13·(1/2)²+4=13·1/4+4=3 1/4+4=7 1/4
(x-11)(x+11)-2(x-1)²=x²-121-2x²+4x-2=-x²+4x-123=-(-1)²+4·(-1)-123=
=-1+(-4)-123=-1-4-123=-128
5(3x-2)(x+1)-(x-y)²+5y(2-5x)+(3+2y)=
=15x²+15x-10x-10-x²+2xy-y²+10y-25xy+2y=
=14x²+5x-7-23xy-y²+12y=14·(1/2)²+5·1/2-7-23·1/2·(-1 1/2)-(-1 1/2)²+12·(-1 1/2)=
=14·1/4+2 1/2-7+17 1/4-2 1/4-18=3 1/2+2 1/2-7+17 1/4-2 1/4-18=
=6-7+15-18=-4
