解
5(x-1)(x+3)-2(x-5)(x-2)
=5(x²+3x-x-3)-2(x²-2x-5x+10)
=5(x²+2x-3)-2(x²-7x+10)
=(5x²-2x²)+(10x+14x)+(-15-20)
=3x²+24x-35
3(x+5)(x-3)-5(x-2)(x+3)
=3(x²+2x-15)-5(x²+x-6)
=(3x²-5x²)+(6x-5x)+(-45+30)
=-2x²+x-15