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(x+y-1)(x^2-xy+y^2+x+y+1)

x^3+y^3+3xy-1
=(x+y)^3-3xy(x+y)+3xy-1
=(x+y-1)(x^2+2xy+y^2+x+y+1)-3xy(x+y-1)
=(x+y-1)(x^2-xy+y^2+x+y+1)

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x^3+y^3+3xy-1
=(x+y)^3-3xy(x+y)+3xy-1
=(x+y-1)(x^2+2xy+y^2+x+y+1)-3xy(x+y-1)
=(x+y-1)(x^2-xy+y^2+x+y+1)

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µª®×....(x+y-1)(x^2-xy+y^2+x+y+1)

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dodo61411@yahoo.com.tw
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x^3+y^3+3xy-1
=(x+y)^3-3xy(x+y)+3xy-1
=(x+y-1)(x^2+2xy+y^2+x+y+1)-3xy(x+y-1)
=(x+y-1)(x^2-xy+y^2+x+y+1)

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The art of doing mathematics consists in finding that special case which contains all the germs of generality

(x+y-1)(x^2-xy+y^2+x+y+1)

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(x+y-1)(x^2-xy+y^2+x+y+1)

(x+y-1)(x^2-xy+y^2+x+y+1)

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