(4x+y)2+(5x-y)(5x+y)-4x(3x-2y)=

(4x+y)2+(5x-y)(5x+y)-4x(3x-2y)= 8x+2y+25x²+5xy-5xy-y²-12x²+8xy= 8x+2y+13x²-y²+8xy

(4x+y)2+(5x-y)(5x+y)-4x(3x-2y)=8x+2y+25x2+5xy-5yx-y2-12x2+8xy=8x+2y+37x2+13xy-5yx-y2

8x+2y+25x2-y+5xy-5xy-x2-14x2+8xy=8x+12x2+2y