4a²-b²-4c²+4bc ；5x²+6y-15x-2xy ；x^3+9+3x²+3x ；2x²+xy-y²-4x+5y-6

4a²-b²-4c²+4bc ；5x²+6y-15x-2xy ；x^3+9+3x²+3x ；2x²+xy-y²-4x+5y-6
4a²-b²-4c²+4bc ；
5x²+6y-15x-2xy ；
x^3+9+3x²+3x ；
2x²+xy-y²-4x+5y-6

4a²-b²-4c²+4bc ；5x²+6y-15x-2xy ；x^3+9+3x²+3x ；2x²+xy-y²-4x+5y-6
4a²-b²-4c²+4bc
=4a²-(b²-4bc+4c²)
=(2a)²-(b-2c)²
=(2a-b+2c)(2a+b-2c)
5x²-15x+2xy-6y
= (5x²-15x) + (2xy-6y)
= 5x(x-3) + 2y(x-3)
= (x-3)(5x+2y)
X²+9+3X²+3X
=(x³+3x²)+(3x+9)
=x²(x+3)+3(x+3)
=(x+3)(x²+3)
2x²+xy-y²-4x+5y-6
=(x+y)(2x-y)-4x+5y-6
=(x+y)(2x-y)+2(x+y)-6x+3y-6
=(x+y)(2x-y+2)-3(2x-y+2)
=(2x-y+2)(x+y-3)