已知x+y=2,xy=0.5,求x2+y2与(x-y)2的值

来源：学生作业帮编辑：作业帮分类：数学作业时间：2024/05/16 10:14:03

x²+y²
=(x²+2xy+y²)-2xy
=(x+y)²-2xy
=2²-2×0.5
=4-1
=3
(x-y)²
=x²-2xy+y²
=(x²+2xy+y²)-4xy
=(x+y)²-4xy
=2²-4×0.5
=4-2
=2
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