a=2(3x-5)-(5x-3)(-2x+1)
=6x-10-(-10x²+5x+6x-3)
=6x-10+10x²-5x-6x+3
=10x²-5x-7
b=(3x+5)²-x(x-4)
=9x²+30x+25-x²+4x
=8x²+34x+25
c=(-2x+7)²-(3-4x)²
=(7-2x)²-(3-4x)²
=49-28x+4x²-(9-24x+16x²)
=49-28x+4x²-9+24x-16x²
=-12x²-4x+40
d=(3x+2)²-2(x-1)(x+1)
=9x²+12x+4-2(x²-1)
=9x²+12x+4-2x²+2
=7x²+12x+6
