$8a(10\%)$ Calculate ${\displaystyle \underset{0}{\overset{4}{}}}{\displaystyle \underset{1}{\overset{x}{}}}\frac{x}{y^2}dxdy$

$b(10\%)$ Calculate ${}_R\frac{\sqrt[\phantom{2}]{2}x+3}{\sqrt[\phantom{2}]{x^2+y^2}}dxdywhereRis$ defined

$as$ a sector ring$with$ a central angle $of$

$\frac{}{4}see$ Figure $2.$

Figure $2$