RÚT GỌN
$\dfrac{2^3 . 3}{2^2 . 3^2 . 5}\\$
$=\dfrac{2^2.2 . 3}{2^2 . 3.3. 5}\\$
$=\dfrac{2}{3.5}\\$
$=\dfrac{2}{15}\\$
$\dfrac{2^4 . 5^2 .7}{2^3 . 5 . 7^2 . 11}\\$
$=\dfrac{ 2^3.2 . 5.5 .7}{2^3 . 5 . 7.7 . 11}$
$=\dfrac{ 2 .5 }{ 7 . 11}$
$=\dfrac{10}{77}$
$\dfrac{2^3 . 3^3 . 5^3 . 7 . 8}{3 . 2^4 . 5^3 . 14}$
$=\dfrac{2^3 . 3^2.3 . 5^3 . 56}{3 . 2^3.2 . 5^3 . 14}$
$=\dfrac{2^3 . 3^2.3 . 5^3 . 4.14}{3 . 2^3.2 . 5^3 . 14}$
$=\dfrac{ 3^2 . 4}{ 2 }$
$=\dfrac{36}{ 2 }$
=$18$
QUY ĐỒNG
$\dfrac{2}{15}$ và $\dfrac{10}{77}$ và $18$
$MC:1155$
$\dfrac{2}{15}$$=\dfrac{2.77}{15.77}$$=\dfrac{154}{1155}$
$\dfrac{10}{77}$ $=\dfrac{10.15}{77.15}$$=\dfrac{150}{1155}$
$18$$=\dfrac{18.1155}{1155}$ $=\dfrac{20790}{1155}$
