$y=x^{\dfrac{1}{3}}(1-x)^{\dfrac{2}{3}}$
$y'=1/3x^{\dfrac{-2}{3}}(1-x)^{\dfrac{2}{3}}-2/3(1-x)^{\dfrac{-1}{3}}x^{\dfrac{1}{3}}$
$y'=\dfrac{1}{3}\sqrt[3]{(\dfrac{1-x}{x})^2}-\dfrac{2}{3}\sqrt[3]{\dfrac{x}{1-x}}$
$t=\sqrt[3]{\dfrac{1-x}{x}}=>y'=0<=>t^3=2=>x=1/3$
Hàm số có 1 CĐ tại $x=1/3$ xét trong $(-\infty;1)$