\(\frac{2}{7}.\frac{12}{15}+\frac{12}{15}.\frac{3}{7}+\frac{12}{15}.\frac{1}{7}+\frac{12}{15}.\frac{1}{7}\)
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\(\frac{15-\frac{15}{7}-\frac{15}{12}-\frac{15}{98}}{18-\frac{18}{7}-\frac{18}{12}-\frac{18}{98}}\)
\(\frac{15-\frac{15}{7}-\frac{15}{12}-\frac{15}{98}}{18-\frac{18}{7}-\frac{18}{12}-\frac{18}{98}}\)= \(\frac{15-15\left(\frac{1}{7}+\frac{1}{12}+\frac{1}{98}\right)}{18-18\left(\frac{1}{7}+\frac{1}{12}+\frac{1}{98}\right)}\)=\(\frac{15\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}{18\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}\)= \(\frac{15}{18}\)=\(\frac{5}{6}\)
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\(\frac{15-\frac{15}{7}-\frac{15}{12}-\frac{15}{98}}{18-\frac{18}{7}-\frac{18}{12}-\frac{18}{98}}\)
\(\frac{15-\frac{15}{7}-\frac{15}{12}-\frac{15}{98}}{18-\frac{18}{7}-\frac{18}{12}-\frac{18}{98}}=\frac{15\left(1+\frac{1}{7}+\frac{1}{12}+\frac{1}{98}\right)}{18\left(1+\frac{1}{7}+\frac{1}{12}+\frac{1}{98}\right)}=\frac{15}{18}=\frac{5}{6}\)
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\(\frac{15-\frac{15}{7}-\frac{15}{12}}{3-\frac{3}{7}-\frac{3}{12}}=?\)
Tính nhanh ạ
Tính nhanh\(\frac{15-\frac{15}{7}-\frac{15}{12}}{3-\frac{3}{7}-\frac{3}{12}}\)
1. Quy đồng mẫu các phân số sau:
a) \(\frac{5}{{12}}\) và \(\frac{7}{{15}}\); b) \(\frac{2}{7};\,\,\frac{4}{9}\) và \(\frac{7}{{12}}\).
2. Thực hiện các phép tính sau:
a) \(\frac{3}{8} + \frac{5}{{24}};\) b) \(\frac{7}{{16}} - \frac{5}{{12}}.\)
1. a) Ta có BCNN(12, 15) = 60 nên ta lấy mẫu chung của hai phân số là 60.
Thừa số phụ:
60:12 =5; 60:15=4
Ta được:
\(\frac{5}{{12}} = \frac{{5.5}}{{12.5}} = \frac{{25}}{{60}}\)
\(\frac{7}{{15}} = \frac{{7.4}}{{15.4}} = \frac{{28}}{{60}}\)
b) Ta có BCNN(7, 9, 12) = 252 nên ta lấy mẫu chung của ba phân số là 252.
Thừa số phụ:
252:7 = 36; 252:9 = 28; 252:12 = 21
Ta được:
\(\frac{2}{7} = \frac{{2.36}}{{7.36}} = \frac{{72}}{{252}}\)
\(\frac{4}{9} = \frac{{4.28}}{{9.28}} = \frac{{112}}{{252}}\)
\(\frac{7}{{12}} = \frac{{7.21}}{{12.21}} = \frac{{147}}{{252}}\)
2. a) Ta có BCNN(8, 24) = 24 nên:
\(\frac{3}{8} + \frac{5}{{24}} = \frac{{3.3}}{{8.3}} + \frac{5}{{24}} = \frac{9}{{24}} + \frac{5}{{24}} = \frac{{14}}{{24}} = \frac{7}{{12}}\)
b) Ta có BCNN(12, 16) = 48 nên:
\(\frac{7}{{16}} - \frac{5}{{12}} = \frac{{7.3}}{{16.3}} - \frac{{5.4}}{{12.4}} = \frac{{21}}{{48}} - \frac{{20}}{{48}} = \frac{1}{{48}}\).
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RÚT GỌNAfrac{12+frac{12}{7}-frac{12}{25}-frac{12}{71}}{4+frac{4}{7}-frac{4}{25}-frac{4}{71}}:frac{3+frac{3}{13}+frac{3}{15}+frac{3}{15}+frac{3}{101}}{5+frac{5}{13}+frac{5}{15}+frac{5}{101}}Bfrac{frac{1}{51}+frac{1}{52}+frac{1}{53}+......+frac{1}{100}}{frac{1}{1.2}+frac{1}{3.4}+frac{1}{5.6}+.......+frac{1}{99.100}}
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RÚT GỌN
\(A=\frac{12+\frac{12}{7}-\frac{12}{25}-\frac{12}{71}}{4+\frac{4}{7}-\frac{4}{25}-\frac{4}{71}}:\)\(\frac{3+\frac{3}{13}+\frac{3}{15}+\frac{3}{15}+\frac{3}{101}}{5+\frac{5}{13}+\frac{5}{15}+\frac{5}{101}}\)
\(B=\frac{\frac{1}{51}+\frac{1}{52}+\frac{1}{53}+......+\frac{1}{100}}{\frac{1}{1.2}+\frac{1}{3.4}+\frac{1}{5.6}+.......+\frac{1}{99.100}}\)
Tính nhanh
\(A=\frac{15-\frac{15}{7}-\frac{15}{12}-\frac{15}{98}}{18-\frac{18}{7}-\frac{18}{12}-\frac{18}{98}}\)
A=15x(1/7-1/12-1/98)/18(1/7-1/12-1/98)
A=15/18
A=5/6
h nhe!!!
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\(A=\frac{15\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}{18\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}\)
\(A=\frac{15}{18}=\frac{5}{6}\)
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\(A=\frac{15-\frac{15}{7}-\frac{15}{12}-\frac{15}{98}}{18-\frac{18}{7}-\frac{18}{12}-\frac{18}{98}}\)
\(\Rightarrow A=\frac{15\left(\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}{18\left(\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}\)
\(\Rightarrow A=\frac{15}{18}=\frac{5}{6}\)
mk làm chuẩn rồi nha
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\(\frac{\frac{5}{12}+\frac{1}{8}-\frac{7}{11}}{\frac{49}{11}-\frac{7}{8}-\frac{35}{12}}\)
\(\frac{5-\frac{5}{3}-\frac{5}{9}-\frac{5}{27}}{-8+\frac{8}{3}+\frac{8}{9}+\frac{8}{27}}:\frac{15-\frac{15}{11}-\frac{15}{121}}{16-\frac{16}{11}-\frac{16}{121}}\)
tính giá trị biểu thứcAfrac{-378.132+189.64}{15+18+21+......+45+48}B1,4.frac{15}{14}-left(frac{4}{5}+frac{2}{5}right):2frac{1}{5}-frac{frac{73}{77}+frac{73}{165}+frac{73}{285}}{frac{25}{24}+frac{15}{180}+frac{20}{285}}Cfrac{7+frac{7}{12}-frac{7}{144}+frac{7}{60}}{5+frac{6}{12}-frac{5}{144}}.frac{frac{3}{4}-frac{3}{16}+frac{3}{64}-frac{3}{256}}{1-frac{1}{4}+frac{1}{16}-frac{1}{34}}-frac{1}{20}
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tính giá trị biểu thức
\(A=\frac{-378.132+189.64}{15+18+21+......+45+48}\)
\(B=1,4.\frac{15}{14}-\left(\frac{4}{5}+\frac{2}{5}\right):2\frac{1}{5}-\frac{\frac{73}{77}+\frac{73}{165}+\frac{73}{285}}{\frac{25}{24}+\frac{15}{180}+\frac{20}{285}}\)
\(C=\frac{7+\frac{7}{12}-\frac{7}{144}+\frac{7}{60}}{5+\frac{6}{12}-\frac{5}{144}}.\frac{\frac{3}{4}-\frac{3}{16}+\frac{3}{64}-\frac{3}{256}}{1-\frac{1}{4}+\frac{1}{16}-\frac{1}{34}}-\frac{1}{20}\)
