問題：次の関数を積分せよ
- (1) \( \displaystyle \int 3^x dx \)
- (2) \( \displaystyle \int 2^xx^2 dx \)
- (3) \( \displaystyle \int_{0}^{1} \dfrac{1}{x^2 + 1} dx \)
- (4) \( \displaystyle \int_{0}^{1} \dfrac{1}{x^3 + 1} dx \)
- (5) \( \displaystyle \int_{0}^{1} \left( x^2 + \dfrac{x}{\sqrt{1 + x^2}} \right) \biggl(1 + \dfrac{x}{(1 + x^2)\sqrt{1 + x^2}} \biggr) dx \)