因式分解x立方加减y立方

过程

x^3+y^3=(x+y)(x^2-xy+y^2) x^3-y^3=(x-y)(x^2+xy+y^2) 这是公式,分别叫立方差和立方和公式,x^3+y^3=x^3+x^2y-x^2y-xy^2+xy^2+y^3=x^2(x+y)-xy(x+y)+y^2(x+y)=(x+y)(x^2-xy+y^2) x^3-y^3=x^3-x^2y+x^2y-xy^2+xy^2-y^3=x^2(x-y)+xy(x-y)+y^2(x-y)=(x-y)(x^2+xy+y^2)
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第1个回答  2014-03-15
x3+y3=(x+y)(x2-xy+y2)x3-y3=(x-y)(x2+xy+y2)