已只x+y=a,x2+y2=b求4x2y2=?

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已只x+y=a,x2+y2=b求4x2y2=?

已只x+y=a,x2+y2=b求4x2y2=?
已只x+y=a,x2+y2=b求4x2y2=?

已只x+y=a,x2+y2=b求4x2y2=?
2xy=(x+y)2-(x2-y2)=a2-b;
4x2y2=(2xy)2=(a2-b)2

(x+y)*2=x2+2xy+y2=b+2xy=a2
2xy=a2-b
4x2y2=(a2-b)2=a4+b2-2a2b

4B

4B

8b2-2a2b+8a4