[tex]c) \frac{ \sqrt{7} }{4} + \frac{ \sqrt{7} }{3} - \frac{ \sqrt{7} }{2} + \frac{5 \sqrt{7} }{12} = \frac{3 \sqrt{7} }{3 \times 4} + \frac{4 \sqrt{7} }{4 \times 3} - \frac{6 \sqrt{7} }{6 \times 2} + \frac{5 \sqrt{7} }{12} = \frac{3 \sqrt{7} }{12} + \frac{4 \sqrt{7} }{12} - \frac{6 \sqrt{7} }{12} + \frac{5 \sqrt{7} }{12} = \frac{3 \sqrt{7} + 4 \sqrt{7} - 6 \sqrt{7} + 5 \sqrt{7} }{12} = \frac{6 \sqrt{7} }{12} = \frac{ \sqrt{7} }{2} [/tex]
