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25 tháng 2 2020
M = \(\frac{2}{1.3}+\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+\frac{2}{9.11}\)
M = \(\frac{2}{1}-\frac{2}{3}+\frac{2}{3}-\frac{2}{5}+\frac{2}{5}-\frac{2}{7}+\frac{2}{7}-\frac{2}{9}+\frac{2}{9}-\frac{2}{11}\)
M = \(\frac{2}{1}-\frac{2}{11}\)
M = \(\frac{20}{11}\)
30 tháng 4 2018
a)\(=\frac{-3}{7}+\frac{15}{26}-\frac{2}{13}+\frac{3}{7}\)
\(=\left(\frac{-3}{7}+\frac{3}{7}\right)-\left(\frac{15}{26}+\frac{2}{13}\right)\)
\(=0-\frac{19}{26}\)
\(=-\frac{19}{26}\)
30 tháng 4 2018
c)\(=\frac{-11}{23}.\left(\frac{6}{7}+\frac{8}{7}\right)-\frac{1}{23}\)
\(=\frac{-11}{23}.2-\frac{1}{23}\)
\(=\frac{-22}{23}-\frac{1}{23}\)
\(=-1\)
8 tháng 8 2016
1) 4824 - 4824 : 24 - 12 = 4824 - 201 - 12 = 4623 - 12 = 4611
MX
1 tháng 4 2017
bài 1 :\(\frac{3}{8}-\frac{1}{5}+\frac{3}{40}=\frac{1}{4}\)
\(\frac{9}{7}\cdot\left(\frac{3}{7}-\frac{1}{2}\right)=-\frac{9}{98}\)
\(-\frac{3}{7}\cdot\frac{5}{9}+\frac{4}{9}\cdot-\frac{3}{7}\cdot\frac{3}{7}=\left(\frac{4}{9}+\frac{5}{9}-1\right)\cdot-\frac{3}{7}=-1\cdot-\frac{3}{7}=\frac{3}{7}\)
bài 2: \(x+\frac{2}{5}=\frac{9}{10}\)
\(x=\frac{9}{10}-\frac{2}{5}\)
\(x=\frac{1}{2}\)
x = \(\frac{9}{10}\)- \(\frac{2}{5}\)
x =\(\frac{9}{10}\) - \(\frac{4}{10}\)
x = \(\frac{5}{10}\) = \(\frac{1}{2}\)
Vậy x = \(\frac{1}{2}\)
ai thấy tớ đúng thì ủng hộ nha
tui đang âm
F
14 tháng 4 2019
\(a)15\frac{3}{13}-\left(3\frac{4}{7}+8\frac{3}{13}\right)\)
\(=15\frac{3}{13}-3\frac{4}{7}-8\frac{3}{13}\)
\(=15\frac{3}{13}-8\frac{3}{13}-3\frac{4}{7}\)
\(=7-3\frac{4}{7}\)
\(=6\frac{7}{7}-3\frac{4}{7}=3\frac{3}{7}\)
\(b)\left(7\frac{4}{9}+4\frac{7}{11}\right)-3\frac{4}{9}\)
\(=7\frac{4}{9}-4\frac{7}{11}-3\frac{4}{9}\)
\(=7\frac{4}{9}-3\frac{4}{9}-4\frac{7}{11}\)
\(=4-4\frac{7}{11}=\frac{7}{11}\)
D
22 tháng 3 2017
\(a)\dfrac{3}{4}-\dfrac{-5}{2}-\dfrac{7}{-24}\)
\(=\dfrac{13}{4}-\dfrac{7}{-24}\)
\(=\dfrac{85}{24}\)
\(b)\dfrac{4}{7}+\dfrac{-5}{8}-\dfrac{3}{28}\)
\(=\dfrac{-3}{56}-\dfrac{3}{28}\)
\(=\dfrac{-9}{56}\)
\(c)\dfrac{7}{36}-\dfrac{8}{-9}+\dfrac{-2}{3}\)
\(=\dfrac{13}{12}\)\(+\dfrac{-2}{3}\)
\(=\dfrac{5}{12}\)
\(d)\dfrac{-1}{2}+\dfrac{3}{7}-\dfrac{1}{9}+\dfrac{-7}{18}+\dfrac{4}{7}\)
\(=\dfrac{-1}{14}-\dfrac{1}{9}+\dfrac{-7}{18}+\dfrac{4}{7}\)
\(=\dfrac{-23}{126}+\dfrac{-7}{18}+\dfrac{4}{7}\)
\(=\dfrac{-4}{7}+\dfrac{4}{7}\)
\(=0\)
\(e)\dfrac{2}{7}+\dfrac{-3}{8}+\dfrac{11}{7}+\dfrac{1}{3}+\dfrac{1}{7}+\dfrac{5}{-8}\)
\(=\dfrac{-5}{56}+\dfrac{11}{7}+\dfrac{1}{3}+\dfrac{1}{7}+\dfrac{5}{-8}\)
\(=\dfrac{83}{56}+\dfrac{1}{3}+\dfrac{1}{7}+\dfrac{5}{-8}\)
\(=\dfrac{305}{168}+\dfrac{1}{7}+\dfrac{5}{-8}\)
\(=\dfrac{47}{24}+\dfrac{5}{-8}\)
\(=\dfrac{4}{3}\)
Q
22 tháng 3 2017
Bài 2 : Tính
a) \(\dfrac{3}{4}-\dfrac{-5}{2}-\dfrac{7}{-24}\)
\(=\dfrac{18}{24}-\dfrac{-60}{24}-\dfrac{-4}{24}\)
\(=\dfrac{18-\left(-60\right)-\left(-7\right)}{24}\)
\(=\dfrac{85}{24}\)
b) \(\dfrac{4}{7}+\dfrac{-5}{8}-\dfrac{3}{28}\)
\(=\dfrac{32}{56}+\dfrac{-35}{56}-\dfrac{6}{56}\)
\(=\dfrac{32+\left(-35\right)-6}{56}\)
\(=\dfrac{-9}{56}\)
c) \(\dfrac{7}{36}-\dfrac{8}{9}+\dfrac{-2}{3}\)
\(=\dfrac{7}{36}-\dfrac{32}{36}+\dfrac{-24}{36}\)
\(=\dfrac{7-32+\left(-24\right)}{36}\)
\(=\dfrac{-49}{36}\)
d) \(\dfrac{-1}{2}+\dfrac{3}{7}-\dfrac{1}{9}+\dfrac{-7}{18}+\dfrac{4}{7}\)
\(=\dfrac{-9}{18}+\dfrac{3}{7}-\dfrac{2}{18}+\dfrac{-7}{18}+\dfrac{4}{7}\)
\(=\left(\dfrac{-9}{18}+\dfrac{-7}{18}-\dfrac{2}{18}\right)+\left(\dfrac{3}{7}+\dfrac{4}{7}\right)\)
\(=\left(-1\right)+1\)
\(=0\)
e) \(\dfrac{2}{7}+\dfrac{-3}{8}+\dfrac{11}{7}+\dfrac{1}{3}+\dfrac{1}{7}+\dfrac{5}{-8}\)
\(=\left(\dfrac{2}{7}+\dfrac{1}{7}+\dfrac{11}{7}\right)+\left(\dfrac{-3}{8}+\dfrac{-5}{8}\right)+\dfrac{1}{3}\)
\(=2+\left(-1\right)+\dfrac{1}{3}\)
\(=1+\dfrac{1}{3}\)
\(=\dfrac{4}{3}\)
7 tháng 3 2017
CÁCH 1 : A = \(\dfrac{235}{11}-\left(\dfrac{8}{5}+\dfrac{81}{11}\right)\)
A = \(\dfrac{235}{11}-\left(\dfrac{88}{55}+\dfrac{405}{55}\right)\)
A = \(\dfrac{235}{11}-\dfrac{493}{55}\)
A = \(\dfrac{1175}{55}+\dfrac{493}{55}\)
A = \(\dfrac{1668}{55}\)
\(5\cdot2^3+7^9:7^7-1^{2020}\\ =5\cdot8+7^2-1\\ =40+49-1\\ =89-1\\ =88\)
\(5.2^3+7^9:7^7-1^{2020}\)
\(=5.8+7^2-1\)
\(=40+49-1\)
\(=88\)