bantu kaka dengan jalannya

[tex] \frac{4}{2 + \sqrt{3} } \times \frac{2 - \sqrt{3} }{2 - \sqrt{3} } = \frac{8 - 4 \sqrt{3} }{4 - 3} = \frac{8 - 4 \sqrt{3} }{1} = 8 - 4 \sqrt{3} [/tex]
nomor 15
[tex] \frac{6}{3 - \sqrt{6} } \times \frac{3 + \sqrt{6} }{3 + \sqrt{6} } = \frac{18 + 6 \sqrt{6} }{9 - 6} = \frac{6(3 + \sqrt{6}) }{3} = 2(3 + \sqrt{6} )[/tex]
nomor 17
[tex] \frac{15}{ \sqrt{7 } + 2} \times \frac{ \sqrt{7} - 2}{ \sqrt{7} - 2 } = \frac{15 \sqrt{7} - 30 }{7 - 4} = \frac{15( \sqrt{7} - 2)}{3} = 5( \sqrt{7} - 2)[/tex]
nomor 16
[tex] \frac{12}{ \sqrt{7} - \sqrt{5} } \times \frac{ \sqrt{7} + \sqrt{5} }{ \sqrt{7} + \sqrt{5} } = \frac{12 \sqrt{7} + 12 \sqrt{5} }{7 - 5} = \frac{12( \sqrt{7} + \sqrt{5}) }{2} = 6( \sqrt{7} + \sqrt{5} )[/tex]
nomor 18

maaf ya ga urut.. tapi semoga membantu :))