(2x-3y)^3+(3x-2y)^3-125(x-y)^3
=(2x-3y)^3+(3x-2y)^3-(5x-5y)^3
令2x-3y=a,3x-2y=b,则5x-5y=a+b
原式=a^3+b^3-(a+b)^3
=a^3+b^3-a^3-3a^2b-3ab^2-b^3
=-3a^2b-3ab^2
=-3ab(a+b)
=-3(2x-3y)(3x-2y)(5x-5y)
=-15(2x-3y)(3x-2y)(x-y)
分解因式:(2x-3y)³+(3x-2y)³-125(x-y)³
解:原式=(2x-3y)³+(3x-2y)³-(5x-5y)³=(2x-3y)³+(3x-2y)³-[(2x-3y)+(3x-2y)]³
=(2x-3y)³+(3x-2y)³-[(2x-3y)³+3(2x-3y)²(3x-2y)+3(2x-3y)(3x-2y)²+(3x-2y)³]
=-3(2x-3y)(3x-2y)[(2x-3y)+(3x-2y)]=-15(2x-3y)(3x-2y)(x-y)
=[(2x-3y)+(3x-2y)][(2x-3y)²-(2x-3y)(3x-2y)+(3x-2y)²]-125(x-y)³
=5(x-y)[13x²+13y²-24xy-6x²-6y²+13xy]-25×5(x-y)(x-y)²
=5(x-y)(7x²+7y²-11xy)-25×5(x-y)(x²-2xy+y²)
=5(x-y)[(7x²+7y²-11xy)-25(x²+y²-2xy)]
=5(x-y)(-18x²-18y²+39xy)
= - 15(x-y)(6x²+6y²-13xy)= -15(x-y)(2x-3y)(3x-2y)
∵A3+B3+C3-3ABC
=(A+B+C)(A2+B2+C2-BC-CA-AB),
若A+B+C=0,便有A3+B3+C3=3ABC,
令A=2x-3y,B=3x-2y,C=5y-5x,
则符合上述条件,易得A3+B3+C3=3ABC.
∴(2x-3y)3+(3x-2y)3-125(x-y)3
=3(2x-3y)(3x-2y)[5(y-x)],
=15(2x-3y)(3x-2y)(y-x),
故答案为:15(2x-3y)(3x-2y)(y-x).
-15(2x-3y)(3x-2y)(x-y)