Diketahui 3/x + 7/y = 27 dan 4/x + 3/y = 17. Nilai 12xy = ....

misal:
1/x= a
1/y= b
[tex]3a + 7b = 27 | \times 4| \\ 4a + 3b = 17 | \times 3| \\ - - - - - - - - \\ 12a + 28b = 108 \\ 12a + 9b = 51 \\ - - - - - - - - ( - ) \\ 19b = 57 \\ b = 3 \\ cari \: a \\4a + 3(3) = 17 \\ 4a + 9 = 17 \\ 4a = 8 \\ a = 2 \\ \\ jadi \\ x = \frac{1}{2} \: dan \: y = \frac{1}{3} \\ \\ 12xy \\ = 12 \times \frac{1}{2} \times \frac{1}{3} \\ = 12 \times \frac{1}{6} \\ = 2[/tex]

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