Svac-xơ nhé
\(P=\frac{1}{16x}+\frac{4}{16y}+\frac{16}{16z}\ge\frac{\left(1+2+4\right)^2}{16\left(x+y+z\right)}=\frac{49}{16}\)
Dấu "=" xảy ra \(\Leftrightarrow\)\(\frac{1}{16x}=\frac{2}{16y}=\frac{4}{16z}\)\(\Leftrightarrow\)\(\frac{1}{x}=\frac{2}{y}=\frac{4}{z}=\frac{1+2+4}{x+y+z}=7\)
Suy ra \(\hept{\begin{cases}x=\frac{1}{7}\\y=\frac{2}{7}\\z=\frac{4}{7}\end{cases}}\)
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