\(P=\dfrac{18}{x}+\dfrac{9}{y}+\dfrac{x}{6}-\dfrac{5y}{12}+2019\)
\(P=\left(\dfrac{x}{2}+\dfrac{18}{x}\right)+\left(\dfrac{y}{4}+\dfrac{9}{y}\right)-\dfrac{1}{3}\left(x+2y\right)+2019\)
\(P\ge2\sqrt{\dfrac{18x}{2x}}+2\sqrt{\dfrac{9y}{4y}}-\dfrac{1}{3}.18+2019=2022\)
Dấu "=" xảy ra khi \(x=y=6\)