a,cho (a+b+c)^2 =3(ab+ac+bc)
cmr:a=b=c
b,Cho(a-b)^2+(b-c)^2+(c-a)^2 +4(ab+bc+ca)=4(a^2+b^2+c^2)
cmr:a=b=c
\(CMR:a^3+b^3+c^3-3abc=\left(a+b+c\right)\left(a^2+b^2+c^2-ab-bc-ac\right)\)
cho a^3+b^3+c^3=3abc .cmr:a+b+c=0 hoặc a=b=c
cho a+b+c=0
cmr:a^3+b^3+c^3=3abc
1.cho x,y thỏa mãn: ax+by=c,bx+cy=a,cx+by=b
CMR:a^3+b^3+c^3=3abc.
2.cho a,b,c khác 0 sao cho:ay-bx/c=cx-az/b=bz-cy/a
CMR:(ax+by+cz)=(x^2+y^2+z^2)(a^2+b^2+c^2)
giai,cho,minh,bai,nay,di cho,a,b,c>=0.CMR:a^3+b^3+c^3>=3abc
\(Cho:a+b+c=\frac{3}{2}.CMR:a^2+b^2+c^2\ge\frac{3}{4}\)
Mn giúp mk vs:
Cho a+b+c=0
CMR:a3+b3+c3-3abc=0
cho a+b+c=0. CMR:a4+b4+c4= 2(a2b2+b2c2+c2a2)