* 0,00(24)
= \(\dfrac{24-0}{9900}=\dfrac{24}{9900}\)
0,(12) = \(\dfrac{12}{99}\)
1,3(4)
= \(1+\dfrac{34-3}{90}=1+\dfrac{31}{90}=\dfrac{121}{90}\)
0,1(25)
\(=\dfrac{125-1}{900}=\dfrac{124}{900}=\dfrac{31}{225}\)
0,(123)= \(\dfrac{123}{999}\)
* tìm x:
a) 0,875 . x = \(\dfrac{3}{4}+2\dfrac{5}{8}\)
\(\dfrac{7}{8}\) . x = \(\dfrac{3}{4}+\dfrac{21}{8}\)
\(\dfrac{7}{8}\) . x = \(\dfrac{6}{8}+\dfrac{21}{8}\)
\(\dfrac{7}{8}\) . x = \(\dfrac{27}{8}\)
x = \(\dfrac{27}{8}\) : \(\dfrac{7}{8}\)
x = \(\dfrac{27}{8}\) . \(\dfrac{8}{7}\)
x = \(\dfrac{27}{7}\)
b) 0,(12) : 1,(6) = x : 0,3
\(\dfrac{12}{99}\) : \(\dfrac{105}{99}\) = x : \(\dfrac{3}{10}\)
\(\dfrac{12}{99}\) . \(\dfrac{99}{105}\) = x : \(\dfrac{3}{10}\)
\(\dfrac{12}{105}\) = x : \(\dfrac{3}{10}\)
\(\dfrac{12}{105}\) . \(\dfrac{3}{10}\) = x
\(\dfrac{6}{175}\) = x
