\(\frac{x}{9}=\frac{1}{18}+\frac{3}{7}\)
=> \(\frac{x}{9}=\frac{7}{126}+\frac{54}{126}\)
=> \(\frac{x}{9}=\frac{61}{126}\)
=> \(x=\frac{61}{126}\cdot9=\frac{61}{14}\)
y đâu ra ?
Ta có : \(\frac{x}{9}-\frac{3}{y}=\frac{1}{18}\)
=> \(\frac{3}{y}=\frac{2x-1}{18}\)
=> \(y\left(2x-1\right)=54\)
Vì \(x,y\inℕ\)nên 2x - 1 \(\inℕ\)
Ta có : \(Ư\left(54\right)=\left\{1;2;3;6;9;18;27;54\right\}\)
| y | 1 | 2 | 3 | 6 | 9 | 18 | 27 | 54 |
| 2x - 1 | 54 | 27 | 18 | 9 | 6 | 3 | 2 | 1 |
| 2x | 55 | 28 | 19 | 10 | 7 | 4 | 3 | 2 |
| x | \(\varnothing\) | 14 | loại | 5 | loại | 2 | loại | 1 |
Vậy \(\left(x,y\right)\in\left\{\left(14,2\right);\left(5,6\right);\left(2,18\right);\left(1,54\right)\right\}\)