问题
解答题
已知:x2+y2=2,xy=-
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答案
(2x2-y2-3xy)-(x2-2y2+xy)
=2x2-y2-3xy-x2+2y2-xy
=x2+y2-4xy,
当x2+y2=2,xy=-
时,原式=2-4×1 2
=2-2=0.1 4
已知:x2+y2=2,xy=-
|
(2x2-y2-3xy)-(x2-2y2+xy)
=2x2-y2-3xy-x2+2y2-xy
=x2+y2-4xy,
当x2+y2=2,xy=-
时,原式=2-4×1 2
=2-2=0.1 4