cho a,b,c la cac so duong thoa man (1/a+1/b+1/c)>=(a+b+c), chung minh a+b+c>=3abc
cho a+b+c=1 va 1/a+1/b+1/c=0.Chung minh rang : a^2+b^2+c^2=0
Cho a b c la cac so thuc. A+b+c=1 va 1/a+1/b+1/c=0. Chung minh A mu 2+ b mu 2+c mu 2=1
cho a,b,c la 3 so khac 0 va a+b+c=0 chung minh rang 1/a^2+b^2-c^2+1/b^2+c^2-a^2+1/c^2+a^2-b^2=0
Cho 1/a+1/b+1/c = 1/(a+b+c) chung minh rang \(\frac{1}{a^{2019}}+\frac{1}{b^{2019}}+\frac{1}{c^{2019}}=\frac{1}{a^{2019}+b^{2019}+c^{2019}}\)
cho a+b+c=1 chung minh (a+bc)(b+ac)(c+ab)=(a+b)^2(a+c)^2(b+c)^2
Cho a, b, c la do dai ba canh cua mot tam giac . Chung minh rang :
\(\frac{1}{a+b-c}+\frac{1}{a+c-b}+\frac{1}{b+c-a}\ge\frac{1}{a+b+c}\)
a+b+c=0 va 1/a+1/b+1/c=1 chung minh a^2+b^2+c^2=1
Cho a/(b+c)+b/(c+a)+c/(a+b)=1. chung minh rang
a^2/(b+c)+b^2/(c+a)+c^2/(a+b)=0