kak tolong di jawab secepatnya dan caranya yang jelas ..........mksh kak

1.
[tex] \frac{6}{ \sqrt{7} - 2} \times \frac{ \sqrt{7} + 2}{ \sqrt{7} + 2} \\ = \frac{6 \sqrt{7} + 12 }{3} \\ = 2 \sqrt{7} + 4[/tex]
2.
[tex] \frac{18}{4 - \sqrt{10} } \times \frac{4 + \sqrt{10} }{4 + \sqrt{10} } \\ = \frac{72 + 18 \sqrt{10} }{6} \\ = 12 + 3 \sqrt{10} [/tex]
3.
[tex] \frac{6}{ \sqrt{7} + \sqrt{5} } \times \frac{ \sqrt{7} - \sqrt{5} }{ \sqrt{7} - \sqrt{5} } \\ = \frac{6 \sqrt{7} - 6 \sqrt{5} }{2} \\ = 3 \sqrt{7} - 3 \sqrt{5} [/tex]
4.
[tex] \frac{15}{2 + \sqrt{7} } \times \frac{2 - \sqrt{7} }{2 - \sqrt{7} } \\ = \frac{30 - 15 \sqrt{7} }{ - 3} \\ = - 10 + 5 \sqrt{7} [/tex]
5.
[tex] \frac{12}{3 + \sqrt{5} } \times \frac{3 - \sqrt{5} }{3 - \sqrt{5} } \\ = \frac{36 - 12 \sqrt{5} }{4} \\ = 9 - 3 \sqrt{5} [/tex]