C
changtrai9xx


cho a, b, c > 0
[tex]\frac{1}{a+b+c+1}[/tex] - [tex]\frac{1}{(a+1)(b+1)(c+1)}[/tex] \leq
[tex]\frac{1}{8}[/tex]
[tex]\frac{1}{a+b+c+1}[/tex] - [tex]\frac{1}{(a+1)(b+1)(c+1)}[/tex] \leq
[tex]\frac{1}{8}[/tex]