甲、乙两名同学进行的因式分解：甲：x²－xy+4x－4y=(x²－xy)+(4x－4y)(分成两组）=x(x－y)+4(x－y)(直接提公因式）=（x－5y)(x+4)乙：a²－b²－c²+2bc=a²－(b²+c²－2bc)(分成两组）=a²－(b－c)²（直接提公因式）=（a+b－c)(a－b+c)请你在他们的解法的启发下,完成下面的因式分解：（1）m³－2m²－4m+8；（2)x²－2xy+y²－9

（1）m³－2m²－4m+8；
=m²(m-2)-4(m-2)
=(m²-4)(m-2)
=(m-2)(m+2)(m-2)
=(m+2)(m-2)²
（2)x²－2xy+y²－9
=(x-y)²-9
=(x-y+3)(x-y-3)

1)原式=（m^3-2m^2)+〔-(4m+8)〕
=m^(m+2)+〔-4(m+2)〕
=(m^2-4)(m+2)
=(m+2)(m-2)(m+2)
=(m-2)(m+2)^2
2)原式=-〔3^2-(x²－2xy+y²)〕
=-〔3^2-(x-y)^2〕
=-(3+x-y)(3-x+y)
=(x-y+3)(x-y-3)

(1)m³－2m²－4m+8＝(m³－2m²）－(4m－8）＝m²(m-2)-4(m-2)＝(m-2)(m+2)(m-2)＝(m+2)(m-2)²(2)x²－2xy+y²－9＝(x-y)²-9＝(x-y+3)(x-y-3)

(1)m³－2m²－4m+8；
=m²(m-2)-4(m-2)
=(m-2)(m+2)(m-2)
=(m+2)(m-2)²
(2)x²－2xy+y²－9
=(x-y)²-9
=(x-y+3)(x-y-3)