In this paper is gived the proof of one interesting algebraic inequality \[ \frac{a^3}x+\frac{b^3}y+\frac{c^3}z\geq\frac{(a+b+c)^3}{3(x+y+z)}, \] where $a,b,c,x,y,z$ are positive real numbers and one effective application of this inequality.