[tex]\bf 5xy\sqrt{28x}+\sqrt{63x^3y^2}\qquad
\begin{cases}
28\to 2\cdot 2\cdot 7\to 2^2\cdot 7\\
----------\\
63\to 3\cdot 3\cdot 7\to 3^2\cdot 7\\
x^3\to x\cdot x\cdot x\to x^2\cdot x
\end{cases}\\\\
-----------------------------\\\\
5xy\sqrt{2^2\cdot 7\cdot x}+\sqrt{3^2\cdot 7\cdot x^2\cdot x\cdot y^2}
\\\\\\
5xy\cdot 2\sqrt{7x}+3\cdot x\cdot y\sqrt{7x}\implies 10xy\sqrt{7x}+3xy\sqrt{7x}
\\\\\\
13xy\sqrt{7x}[/tex]
