[tex]\int {\frac{3}{\sqrt{1-4x^{2}}}} \, dx[/tex]
[tex]= 3\int {\frac{1}{\sqrt{1-4x^{2}}}} \, dx[/tex]
[tex]= 3\int {\frac{1}{\sqrt{4(\frac{1}{4} - x^{2})}}} \, dx[/tex]
[tex]= \frac{3}{2}\int {\frac{1}{\sqrt{\frac{1}{4} - x^{2}}}}\, dx[/tex]
[tex]= \frac{3}{2}sin^{-1}(2x) + C[/tex]