a) 4/7.|x|+1/28=12/28
b)16/2/7:(-3/5)-26/2/7:(-/5)
Câu b 16/2/7 và 26/2/7 là hỗn số nha
Thanks
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a. \(C=\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+...+\frac{1}{61}-\frac{1}{66}\)
\(=\frac{1}{11}-\frac{1}{66}=\frac{5}{66}\)
b. \(D=\frac{2}{3}.\left(\frac{3}{1.4}+\frac{4}{4.7}+...+\frac{3}{97.100}\right)\)
\(=\frac{2}{3}.\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{100}\right)\)
\(=\frac{2}{3}.\left(1-\frac{1}{100}\right)=\frac{2}{3}.\frac{99}{100}=\frac{33}{50}\)
\(C=\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-....-\frac{1}{66}\)
\(C=\frac{1}{11}-\frac{1}{66}=\frac{5}{66}\)
\(D=\frac{2}{3}.\left(\frac{1}{1}-\frac{1}{4}+\frac{1}{4}-....-\frac{1}{100}\right)\)
\(D=\frac{2}{3}.\left(1-\frac{1}{100}\right)=\frac{2}{3}.\frac{99}{100}=\frac{33}{50}\)
Câu 1:
\(-12+\left(16-11\right).4=-12+5.4=-12+20=8\)
Câu 2:
\(2\dfrac{3}{7}+1\dfrac{4}{7}=\dfrac{17}{7}+\dfrac{11}{7}=\dfrac{17+11}{7}=\dfrac{28}{7}=4\)
Câu 3:
\(\dfrac{-2}{3}.\dfrac{4}{5}+\dfrac{1}{5}:\dfrac{9}{11}=\dfrac{-8}{15}+\dfrac{11}{45}=\dfrac{-13}{45}\)
Câu 1:
\(-12+\left(16-11\right).4=-12+5.4=-12+20=8\)
Câu 2:
\(2\dfrac{3}{7}+1\dfrac{4}{7}=\dfrac{17}{7}+\dfrac{11}{7}=\dfrac{28}{7}=4\)
Câu 3:
\(\dfrac{-2}{3}.\dfrac{4}{5}+\dfrac{1}{5}:\dfrac{9}{11}=\dfrac{-8}{15}+\dfrac{1}{5}.\dfrac{11}{9}=\dfrac{-8}{15}+\dfrac{11}{45}=\dfrac{-13}{45}\)
2/5 + 11/15 = 17/15
7/8 - 7/9 = 7/72
11/13 x 26/31 = 22/31
16/24 : 4 = 1/6
30 : 6/5 = 25
9/16 : 4 = 9/64
1/2 : 1/3 x 8/15 = 3/2 x 8/15 = 4/5
a) Ta có: \(\dfrac{-5}{7}\left(\dfrac{14}{5}-\dfrac{7}{10}\right):\left|-\dfrac{2}{3}\right|-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)+\dfrac{10}{3}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)
\(=\dfrac{-5}{7}\cdot\dfrac{3}{2}\cdot\dfrac{21}{10}-\dfrac{3}{4}\cdot\dfrac{56}{3}+\dfrac{10}{3}\cdot\dfrac{8}{15}\)
\(=\dfrac{-9}{4}-14+\dfrac{16}{9}\)
\(=\dfrac{-1621}{126}\)
b) Ta có: \(\dfrac{17}{-26}\cdot\left(\dfrac{1}{6}-\dfrac{5}{3}\right):\dfrac{17}{13}-\dfrac{20}{3}\left(\dfrac{2}{5}-\dfrac{1}{4}\right)+\dfrac{2}{3}\left(\dfrac{6}{5}-\dfrac{9}{2}\right)\)
\(=\dfrac{-17}{26}\cdot\dfrac{13}{17}\cdot\dfrac{-3}{2}-\dfrac{20}{3}\cdot\dfrac{3}{20}+\dfrac{2}{3}\cdot\dfrac{-33}{10}\)
\(=\dfrac{3}{4}-1-\dfrac{11}{5}\)
\(=-\dfrac{49}{20}\)