Question

[Văn Tùng]

1) \(\int\limits^2_1\dfrac{\sqrt{x^2-1}}{x}dx\)

2) \(\int x.\sqrt{1-x^4}dx\)

3)\(\int\dfrac{1}{x^2.\sqrt{25-x^2}}dx\)

4) \(\int\dfrac{\sqrt{x^2-9}}{x^3}dx\)