곡선

$\displaystyle y= \frac{2 \sqrt {x ^ {3}}} {3} - \frac{\sqrt {x}} {2} \left (1 \leq x \leq 2 \right)$

의 길이는?

• ①$\displaystyle \frac{11 \sqrt {2}} {6} - \frac{7} {6}$
• ②$\displaystyle \frac{9 \sqrt {2}} {6} - \frac{5} {6}$
• ③$\displaystyle \frac{7 \sqrt {2}} {6} - \frac{1} {2}$
• ④$\displaystyle \frac{5 \sqrt {2}} {6} - \frac{1} {6}$
• ⑤$\displaystyle \frac{\sqrt {2}} {2} + \frac{1} {6}$