第九題:    \(\displaystyle 4 \frac{H^{2}_{3}}{\frac{7!}{3!3!}} \)

\(\displaystyle -\frac{1}{2}\int^{2}_{0}\sqrt{4-x^2}d(4-x^2)=-\frac{1}{2}\times\frac{2}{3}(4-x^2)^{\frac{3}{2}}|^{2}_{0}\)