a) 3(x-3)-(5x+1)= 3x-9-5x-1= -2x -10 = -2(x+5)
b) -3(2x+3)+5(2x-8)= -6x-9+10x-40 = 4x - 49
c) (x-3)(x+4)+2(x-3)(2x+1)= x²+4x-3x-12+2(2x²+x-6x-3)=x²+x-12+4x²-10x-6=
=5x²-9x-18
d)(x-1)(2x+3)-(4x-2)(x+3)= 2x²+3x-2x-3-(4x²+12x-2x-6) = 2x²+x-3-4x²-10x+6=
=-2x²-9x+3