a)
(2x-1)(3x+2)-7x(x+1)=6x^2+4x-3x-2-7x^2-7x=-x^2-6x-2
b)
(x-5)^2(x-\sqrt2)+x^2(2-x\sqrt2)=
(x^2-10x+25)(x-\sqrt2)+2x^2-\sqrt2x^3=
x^3-\sqrt2x^2-10x^2+10\sqrt2x+25x-25\sqrt2+2x^2-\sqrt2x^3=
x^3-2\sqrt2x^3-8x^2-\sqrt2x^2+25x+10\sqrt2x-25\sqrt2=
(1-2\sqrt2)x^3-(8+\sqrt2)x^2+(25+10\sqrt2)x-25\sqrt2
c)
-x(4x-6)-(2x+1)(2x-1)=-4x^2+6x-(4x^2-1)=-4x^2+6x-4x^2+1=-8x^2+6x+1
Skorzystałam ze wzoru skróconego mnożenia
(a+b)(a-b)=a^2-b^2
d)
(3x^2-2x+5)(x-2)-(4+3x)^2=
3x^3-6x^2-2x^2+4x+5x-10-(16+24x+9x^2)=3x^3-8x^2+9x-10-16-24x-9x^2=3x^3-17x^2-15x-26