Đáp án:
\(\begin{array}{l}
b) - {x^2}y\\
d)\dfrac{{4x}}{{5y}}
\end{array}\)
Giải thích các bước giải:
\(\begin{array}{l}
b)2{y^2}.\sqrt {\dfrac{{{x^4}}}{{4{y^2}}}} = 2{y^2}.\dfrac{{{x^2}}}{{2\left| y \right|}}\\
= - 2{y^2}.\dfrac{{{x^2}}}{{2y}}\\
= - {x^2}y\\
d)\dfrac{2}{{10}}.{x^3}{y^3}.\dfrac{{\sqrt {16} }}{{\sqrt {{x^4}{y^8}} }}\\
= \dfrac{1}{5}.{x^3}{y^3}.\dfrac{4}{{{x^2}{y^4}}}\\
= \dfrac{{4x}}{{5y}}
\end{array}\)
