Question

Cho a , b ,c >0 .Cm 1/a +1/b +1/c >= 9 nếu a+b+c=1

Answer 1

Áp dụng Bđt \(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}\ge\frac{9}{a+b+c}\)ta có:

\(\frac{1}{a}+\frac{1}{b}+\frac{1}{c}\ge\frac{9}{a+b+c}=9\)(Đpcm)