0\\x=\frac{6}{y}, x>0" alt="xy=6, x>0\\x=\frac{6}{y}, x>0" align="absmiddle" class="latex-formula"> значит и y>0
0\\y=3\\x=\frac{6}{y}=\frac{6}{3}=2" alt="z(y)=\frac{18+2y^2}{y}\\z`(y)=\frac{(18+2y^2)`*y-(18+2y^2)y`}{y^2}=\frac{4y^2-18-2y^2}{y^2}=\frac{2y^2-18}{y^2}=\frac{2(y-3)(y+3)}{y^2}\\z`(y)=0\\\frac{2(y-3)(y+3)}{y^2}=0\\y=+-3, y>0\\y=3\\x=\frac{6}{y}=\frac{6}{3}=2" align="absmiddle" class="latex-formula">
-наименьшее