19. 求Σ_k=1^∞ 3/((3k-1)(3k+2)) =？ (A)1/5 (B)1/4(C)1/3(D) 1/2

24. 將積分區域等分為 4 段，以中點法求\( \int_{-1}^{1} 10^x dx \)的近似值，結果為下列哪一選項？ (A) 0 (B) \( \frac{1}{2} \left( \frac{1}{\frac{3}{10^4}} + \frac{1}{\frac{1}{10^4}} + 10^{\frac{1}{4}} + 10^{\frac{3}{4}} \right) \) (C)\( \frac{1}{4} \left( \frac{1}{10} + \frac{2}{\sqrt{10}} + 2 + 2\sqrt{10} + 10 \right) \) (D)\( \frac{1}{6} \left( \frac{1}{10} + \frac{4}{\sqrt{10}} + 2 + 4\sqrt{10} + 10 \right) \)