大话一现
春芽
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x^5+y^5-x^3y^2-x^2y^3
=x^3(x^2-y^2)-y^3(x^2-y^2)
=(x^2-y^2)(x^3-y^3)
=(x+y)(x-y)(x-y)(x^2+xy+y^2)
=(x-y)^2(x+y)(x^2+y^2+xy)
因为x>=0,y>=0
所以x+y>=0 x^2+y^2+xy>=0 (x-y)^2>=0
所以x^5+y^5-x^3y^2-x^2y^3>=0
即x^5+y^5>=x^3y^2+x^2y^3
1年前
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