\(\begin{array}{l}
+ )\,\,\,\left( {{x^2} - \dfrac{2}{5}y} \right).\left( {{x^2} - \dfrac{2}{5}y} \right) = {\left( {{x^2} - \dfrac{2}{5}y} \right)^2}\\
= {\left( {{x^2}} \right)^2} - 2.{x^2}.\dfrac{2}{5}y + {\left( {\dfrac{2}{5}y} \right)^2} = {x^4} - \dfrac{4}{5}{x^2}y + \dfrac{4}{{25}}{y^2}\\
+ )\,\,{\left( {2x + {y^2}} \right)^3}\\
= {\left( {2x} \right)^3} + 3.{\left( {2x} \right)^2}.{y^2} + 3.2x.{\left( {{y^2}} \right)^2} + {\left( {{y^2}} \right)^3}\\
= 8{x^3} + 12{x^2}{y^2} + 6x{y^4} + {y^8}\\
+ )\,\,{\left( {x + \dfrac{1}{4}} \right)^2} = {x^2} + 2.x.\dfrac{1}{4} + {\left( {\dfrac{1}{4}} \right)^2} = {x^2} + \dfrac{1}{2}x + \dfrac{1}{{16}}
\end{array}\)
