1) -6a+9b-12c-8a-10b+14c-3a+2b-c= -17a +b+c
2) 3(x²-4x-3)-2(x²-5x-4)-(3x²+4x-3)= 3x²-12x-9-2x²+10x+8-3x²-4x+3= -2x²-6x+2= = -2(x²+3-1)
3)(3x+4)(2x-5)-(x+3)(x-6)-(x+2)(x-1)= 6x²-15x+8x-20-(x²-6x-3x+18)-(x²-x+2x-2)
= 6x²-15x+8x-20-x²+6x+3x-18-x²+x²+2x-2= 5x² +4x-40= 5x²+4(x-10)
4)(5x-3)²-(4x-2)²= 25x²-30x+9-16x²+16x-4= 9x² -14x +5
5)16(3x+2)²-9(x+1)²= 16(9x²+12x+4)-9(x²+2x+1)= 144x²+192x+64-9x²-18x-9
= 135x² +174x+55