(X+Y+Z)^2=x^2+y^2+z^2+2(xy+yz+xz)
=a^2=x^2+y^2+z^2+2b
所以x^2+y^2+z^2=a^2-2b
已知X+Y+Z=a,XY+YZ+XZ=b,求X*X+Y*Y+Z*Z的值
已知X+Y+Z=a,XY+YZ+XZ=b,求X*X+Y*Y+Z*Z的值
数学人气：238 ℃时间：2019-12-25 14:00:25
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