1.(x+y)³(x-y)-(x+y)(x-y)³
2.25(x-2y)³+4(2y-x)
3.9x²-16(a+b)²
1.(x+y)³(x-y)-(x+y)(x-y)³
2.25(x-2y)³+4(2y-x)
3.9x²-16(a+b)²
1.(x+y)³(x-y)-(x+y)(x-y)³=(x+y)(x-y)【.(x+y)²-(x-y)²】=(x²-y²)(4xy)
2.25(x-2y)³+4(2y-x)=(x-2y)[25(x-2y)²-4]=(x-2y)(5x-10y+2)(5x-10y-2)
3.9x²-16(a+b)²=(3x+4a+4b)(3x-4a-4b)