分类：教育/科学-学习帮助
问题：已知x２
同上
回答：z^2=x^2-y^2=(x+y)(x-y) 
y^2=x^2-z^2=(x+z)(x-z) 

x^3-y^3-z^3 
=(x-y)(x^2+xy+y^2)-z(x+y)(x-y) 
=(x-y)(x^2+xy+y^2-zx-zy) 
=(x-y)(x^2-zx+xy-zy+y^2) 
=(x-y)((x*(x-z)+y(x-z)+(x+z)(x-z)) 
=(x-y)(x-z)(2x+y+z)