How can I rewrite these substitution?

What substitution will be the most helpful for evaluating this integral? V x=3tan6 x=3sec6 x=3sin9 Rewrite the given integral using this substitution. 1! a ,l I dX I (D) d9 3 x VQ+X n I? E (Simplify your answers. Type exact answers.) Evaluate the following integral using trigonometric substitution. 1 43 I 4 x2 + 1 dx 0 What substitution will be the most helpful for evaluating this integral? x=sec9 x=sin6 V x=tan6 Rewrite the given integral using this substitution. % I41/x2+1dx= I( de 0 O (Simplify your answers. Type exact answers.)