plsssssssss giúp mai đi hc r

Ta có:

`ab=ƯCLN(a,b)*BCN N(a,b)`

`=>ƯCLN(a,b)=(ab)/(BCN N(a,b))`

`=>ƯCLN(a,b)=(180)/60`

`=>ƯCLN(a,b)=3`

Đặt `a=3a_1;b=3b_1  (a_1,b_1inNN`*`;ƯCLN(a_1,b_1)=1)`

Ta có:

`3a_1*3b_1=180`

`=>9(a_1*b_1)=180`

`=>a_1*b_1=20=1*20=4*5`

Ta có bảng sau:

$\begin{array}{|c|c|c|}\hline \text{}a_1&\text{}1&\text{}20&4&5\\\hline \text{}b_1&\text{}20&\text{}1&5&4\\\hline \text{}a&\text{}3&\text{}60&12&15\\\hline \text{}b&\text{}60&\text{}3&15&12\\\hline\end{array}$

Vậy `(a,b)in{(3,60);(60,3);(12,15);(15,12)}`