a) $x(x+1) - 3x(-x+3) + 2(x^2-x)=$ $=x^2+x +3x^2-9x + 2x^2-2x=$ $=6x^2-10x$ b) $(x+2) (x-3) - (x-2) (x+3)=$ $=x^2-3x+2x-6-(x^2+3x-2x-6)=$ $=x^2-3x+2x-6-x^2-3x+2x+6=$ $=-2x$ c) $(3x-5) (x-3) - (x+1) (3x-7)=$ $=3x^2-9x-5x+15-(3x^2-7x+3x-7)=$ $=3x^2-9x-5x+15- 3x^2+7x-3x+7=$ $=-10x+22$ d) $-3x (x+7) (…)