已知x(x+1)-(x²+y)=3,求2分之x²+y²-xy的值
人气:261 ℃ 时间:2019-08-21 11:23:41
解答
x(x+1)-(x²+y)=3
x²+x-x²-y=3
x-y=3
2分之(x²+y²)-xy
=2分之(x²-2xy+y²)
=2分之(x-y)²
=2分之3²
=2分之9sorry,是2分之x²+y² 然后再-xy的值我早猜到了,我就是这么解的哦,还是没看出来,哈哈!
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