Áp dụng quy tắc khai phương một thương, hãy tính :

a) 9169−−−−√ = \(\sqrt{\dfrac{3^2}{13^2}}\) = \(\left|\dfrac{3}{13}\right|\) = \(\dfrac{3}{13}\)

b) 25144−−−−√ = \(\sqrt{\dfrac{5^2}{12^2}}\) = \(\left|\dfrac{5}{12}\right|\) = \(\dfrac{5}{12}\)

c) 1916−−−−√ = \(\sqrt{\dfrac{25}{16}}\) = \(\sqrt{\dfrac{5^2}{4^2}}\) = \(\left|\dfrac{5}{4}\right|\) = \(\dfrac{5}{4}\)

d) 2781−−−−√ = \(\sqrt{\dfrac{169}{81}}\) = \(\sqrt{\dfrac{13^2}{9^2}}\) = \(\left|\dfrac{13}{9}\right|\) = \(\dfrac{13}{9}\)

a) x.y = 14,3. 2,5 = 35,75

    x : y = 14,3 : 2,5 = 5,72

b)

\(\begin{array}{*{20}{l}}{\left( { - 14,3} \right).\left( { - 2,5} \right) = 35,75\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;}\\{\left( { - 14,3} \right):\left( { - 2,5} \right) = 5,72\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;\;\;}\\{\left( { - 14,3} \right).\left( {2,5} \right) =  - 35,75}\\{\left( { - 14,3} \right):\left( {2,5} \right) =  - 5,72\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;}\\{\left( {14,3} \right){\rm{ }}.\left( { - 2,5} \right) =  - 35,75\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;{\rm{ }}\;}\\{\left( {14,3} \right){\rm{ }}.\left( { - 2,5} \right) =  - 5,72}\end{array}\)      

3/13;5/12;5/4;13/9

9 169 = 9 169 = 3 13

25 144 = 25 144 = 5 12

1 9 16 = 25 16 = 25 16 = 5 4

2 7 81 = 169 81 = 169 81 = 13 9

= 66

75 . 48 = 25 . 3 . 3 . 16 = 25 . 3 2 . 16 = 5 . 3 . 4 = 60