若x2+y2=12,xy=4,则x-y=______.
人气:434 ℃ 时间:2019-10-27 17:42:48
解答
∵x2+y2=12,xy=4,
∴(x-y)2=x2+y2-2xy=12-8=4,
则x-y=±2.
故答案为:±2
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