(1) (x-3)(x²-2x+3)=x³-2x²+3x
-3x²+6x-9=
x³-5x²+9x-9
(2) (2x²-6)(4x+1)/2=(x²-3)(4x+1)=
4x³+x²-12x-3
(3) (2x-5)(3x+2)²=
(2x-5)(9x²+12x+4)=
18x³+24x²+8x
(4) (5x+8)(6x+2)-5x(x+6)=
30x²+58x+16-5x²-30x=
25x²+28x+16
(5) (x+6)(2x+5)/2-x(x+1)=
(2x²+17x+30)/2-x²-x=
x²+17x/2+15-x²-x=
15x/2+15