( x^2 - 2x - 2 )(x^2 - 2x + 4 )+9已知 x^2 + 2xy + y^2 - 6y - 10 = 0 ,求xy?注意是2个题目~

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( x^2 - 2x - 2 )(x^2 - 2x + 4 )+9已知 x^2 + 2xy + y^2 - 6y - 10 = 0 ,求xy?注意是2个题目~
( x^2 - 2x - 2 )(x^2 - 2x + 4 )+9
已知 x^2 + 2xy + y^2 - 6y - 10 = 0 ,求xy?
注意是2个题目~

( x^2 - 2x - 2 )(x^2 - 2x + 4 )+9已知 x^2 + 2xy + y^2 - 6y - 10 = 0 ,求xy?注意是2个题目~
1、( x^2 - 2x - 2 )(x^2 - 2x + 4 )+9
=(x^2-2x+1-3)(x^2-2x+1+3)+9
=[(x-1)^2-3][(x-1)^2+3]+9
=(x-1)^4-9+9
=(x-1)^4

设t=x^2-2x
原式=t^2+2t+1=(t+1)^2