A
anhson97


bài 1
choa+b+c=0
CM:a^3+b^3+c^3=3abc
bài 2
cho (a^2+b^2+c^2).(x^2+y^2+z^2)=(ax+by+cz)^2
CMx/a=b/y=c/z
choa+b+c=0
CM:a^3+b^3+c^3=3abc
bài 2
cho (a^2+b^2+c^2).(x^2+y^2+z^2)=(ax+by+cz)^2
CMx/a=b/y=c/z
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