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\(\frac{1}{2}+\frac{1}{3}=\frac{1.3}{2.3}+\frac{1.2}{2.3}=\frac{3}{6}+\frac{2}{6}=\frac{5}{6}\)
\(\frac{7}{8}+\frac{2}{9}=\frac{63}{72}+\frac{16}{72}=\frac{79}{72}\)
\(\frac{17}{9}-\frac{11}{9}=\frac{6}{9}=\frac{2}{3}\)
\(\frac{1}{2}:\frac{1}{3}=\frac{1}{2}.\frac{3}{1}=\frac{3}{2}\)
\(\frac{1}{8}x\frac{7}{8}=\frac{7}{64}\)
Ủng hộ nhé !
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1+2+3+4+5+6+7+8+9+1+2+3+4+5+6+7+8+9+1+2+3+4+5+6+7+8+9=135
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4/9 x 3/8 + 5/8 = 1/6 + 5/8 = 19/24
1/3 : 1/6 - 5/11 = 2 - 5/11 = 17/11
1/6 : 1/4 x 9/8 = 2/3 x 9/8 = 3/4
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tổng quát: \(\frac{1}{n.\left(n+1\right)}=\frac{1}{n}-\frac{1}{n+1}\)
Ta có: \(\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}\)
\(=\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}\)
\(=\frac{1}{3}-\frac{1}{10}=\frac{10}{30}-\frac{3}{30}=\frac{7}{30}\)
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\(\left(\dfrac{2}{7}+\dfrac{5}{7}\right)+\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+\left(\dfrac{3}{8}+\dfrac{4}{8}+\dfrac{1}{8}\right)+\left(\dfrac{1}{9}+\dfrac{8}{9}\right)=1+1+1+1=4\)
bằng 73/9 nhé
1/9 + 1/8 = 17/72