\(\frac{2}{25.27}\)+\(\frac{2}{10.12}\)+
K
Khách

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9 tháng 8 2019

con cac

\(D=\frac{2}{25.27}+2\left(\frac{1}{10}-\frac{1}{12}+\frac{1}{12}-\frac{1}{14}+...+\frac{1}{48}-\frac{1}{50}\right)\)

\(D=2.\left(\frac{1}{25}-\frac{1}{27}\right)+2\left(\frac{1}{10}-\frac{1}{50}\right)\)

\(D=2.\frac{2}{675}+2.\frac{2}{25}\)

\(D=2.\left(\frac{2}{675}+\frac{2}{25}\right)\)

\(D=2.\frac{56}{675}\)

\(D=\frac{112}{675}\)

Study well 

a, Sai

b, Đúng

c, đúng 

d, Sai

20 tháng 9 2020

a,\(2\frac{2}{5}+1\frac{2}{5}=3\frac{2}{5}\left(S\right)\)

b,\(6\frac{3}{4}-1\frac{1}{4}=5\frac{2}{4}\left(\text{Đ}\right)\)

c,\(3\frac{1}{2}\times2\frac{2}{3}=9\frac{1}{3}\left(\text{Đ}\right)\)

d,\(4\frac{1}{6}\div2\frac{1}{5}=2\frac{5}{6}\left(S\right)\)

22 tháng 10 2017

a, 6/9+5/7+1/3=2/3+5/7+1/3=5/7+1=12/7

b, 17/7+6/5-20/14=17/7+6/5-10/7=6/5+1=11/5

c,2/5x1/4+3/4x2/5=2/5x(1/4+3/4)=2/5x1=2/5

d, 6/11:4/6+5/11:2/3=6/11:2/3+5/11:2/3=(6/11+5/11):2/3=3/2

nha

25 tháng 9 2020

\(\frac{8}{9}+\frac{1}{3}=\frac{8}{9}+\frac{3}{9}=\frac{11}{9}\)

\(\frac{8}{9}+\frac{1}{3}=\frac{8}{9}+\frac{3}{9}=\frac{11}{9}\)

\(\frac{24}{15}-\frac{20}{25}=\frac{24}{15}-\frac{4}{5}=\frac{24}{15}-\frac{12}{15}=\frac{12}{15}\)

\(3\frac{1}{6}\times2\frac{3}{5}=\frac{19}{6}\times\frac{13}{5}=\frac{247}{30}\)

\(2\frac{1}{10}\div2\frac{2}{5}=\frac{21}{10}\div\frac{12}{5}=\frac{21}{10}\times\frac{5}{12}=\frac{7}{8}\)

19 tháng 9 2020

\(a.1\frac{1}{3}+2\frac{1}{2}\)

\(=\frac{4}{3}+\frac{5}{2}\)

\(=\frac{8}{6}+\frac{15}{6}\)

\(=\frac{23}{6}\)

\(b.3\frac{2}{5}-1\frac{1}{7}\)

\(=\frac{17}{5}-\frac{8}{7}\)

\(=\frac{119}{35}-\frac{40}{35}\)

\(=\frac{79}{35}\)

\(c.3\frac{1}{2}.1\frac{1}{7}\)

\(=\frac{7}{2}.\frac{8}{7}\)

\(=4\)

\(d.4\frac{1}{6}:2\frac{1}{3}\)

\(=\frac{25}{6}:\frac{7}{3}\)

\(=\frac{25}{6}.\frac{3}{7}\)

\(=\frac{25}{14}\)

7 tháng 8 2017

\(\frac{10}{18}+\frac{4}{9}+\frac{26}{10}+\frac{12}{5}+\frac{9}{15}\)

\(=\frac{5}{9}+\frac{4}{9}+\frac{13}{5}+\frac{12}{5}+\frac{3}{5}\)

\(=\left(\frac{5}{9}+\frac{4}{9}\right)+\left(\frac{13}{5}+\frac{12}{5}+\frac{3}{5}\right)\)

\(=1+\frac{28}{5}\)

\(=\frac{33}{5}\)

7 tháng 8 2017

Ta có:

a) \(\frac{10}{18}+\frac{4}{9}+\frac{26}{10}+\frac{12}{5}+\frac{9}{15}=\frac{5}{9}+\frac{4}{9}+\frac{13}{5}+\frac{12}{5}+\frac{9}{15}=1+1+\frac{9}{15}=1\frac{9}{15}\)

b)\(\frac{10}{18}+\frac{4}{9}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}=\left(\frac{5}{9}+\frac{4}{9}\right)+\left(\frac{16}{128}+\frac{8}{128}+\frac{4}{128}+\frac{2}{128}+\frac{1}{128}\right)\)

\(=1+\frac{31}{128}=1\frac{31}{128}\)