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9 tháng 1 2022
a: \(\Leftrightarrow-2x=-\dfrac{1}{3}-\dfrac{1}{8}-\dfrac{5}{7}=-\dfrac{197}{168}\)
hay x=197/336
c: \(\Leftrightarrow5x=9+\dfrac{6}{18}-\dfrac{2}{7}=\dfrac{190}{21}\)
hay x=38/21
TT
3
VT
4 tháng 4 2022
\(\dfrac{2x}{18}\) \(=\) \(\dfrac{5}{9}\) \(+\) \(\dfrac{2}{3}\)
\(\dfrac{2x}{18}\) \(=\) \(\dfrac{11}{9}\)
\(2x . 9\) \(=\) \(18 . 11\)
\(2x . 9\) \(=\) \(198\)
\(2x \) \(=\) \(198 : 9\)
\(2x\) \(=\) \(22\)
\(x\) \(=\) \(22 : 2 = 11\)
MN
9 tháng 5 2021
\(a.\)
\(-\dfrac{2}{9}+\dfrac{7}{-9}=\dfrac{-2}{9}-\dfrac{7}{9}=\dfrac{-2-7}{9}=\dfrac{-9}{9}=-1\)
\(b.\)
\(\dfrac{1}{-6}+\dfrac{13}{-15}=-\dfrac{1}{6}-\dfrac{13}{15}=\dfrac{\left(-1\right)\cdot5-13\cdot2}{30}=\dfrac{-5-26}{30}=\dfrac{-31}{30}\)
\(c.\)
\(\dfrac{5}{-6}+\dfrac{-5}{12}+\dfrac{7}{18}=\dfrac{-5}{6}-\dfrac{5}{12}+\dfrac{7}{18}=\dfrac{\left(-5\right)\cdot6-5\cdot3+7\cdot2}{36}=\dfrac{-31}{36}\)
9 tháng 5 2021
a) \(\dfrac{-2}{9}+\dfrac{7}{-9}=\dfrac{-2+-7}{9}=-1\)
b)\(\dfrac{1}{-6}+\dfrac{13}{-15}=\dfrac{-5}{30}+\dfrac{26}{30}=\dfrac{-5+26}{30}=\dfrac{7}{10}\)
c) \(\dfrac{5}{-6}+\dfrac{-5}{12}+\dfrac{7}{18}=\dfrac{-30}{36}+\dfrac{-15}{36}+\dfrac{18}{36}=\dfrac{-30+-15+18}{36}=\dfrac{-3}{4}\)
1 tháng 7 2023
2:
a: 2/9-x=-5/9
=>x=2/9+5/9=7/9
b: x-7/13=1/2
=>x=1/2+7/13=27/26
S
12 tháng 2
câu a
\(\dfrac{7}{4}+\dfrac{3}{2}+\dfrac{-9}{16}\\ =\dfrac{28}{16}+\dfrac{24}{16}-\dfrac{9}{16}=\dfrac{43}{16}\)
câu b
\(-\dfrac{2}{7}+\dfrac{3}{5}+\dfrac{9}{7}+\dfrac{-18}{5}\\ =-\dfrac{10}{35}+\dfrac{21}{35}+\dfrac{45}{35}-\dfrac{126}{35}\\ =-\dfrac{70}{35}=-2\)
câu c
\(-\dfrac{5}{13}+\dfrac{11}{10}-\dfrac{-9}{10}+\dfrac{-8}{13}\\ =-\dfrac{5}{13}+\dfrac{11}{10}+\dfrac{9}{10}-\dfrac{8}{13}\\ =-\dfrac{50}{130}+\dfrac{143}{130}+\dfrac{117}{130}-\dfrac{80}{130}\\ =\dfrac{130}{130}=1\)
bài 2
câu a
\(\dfrac{2}{9}-x=-\dfrac{5}{9}\\ x=\dfrac{2}{9}-\dfrac{-5}{9}\\ x=\dfrac{7}{9}\)
câu b
\(x+\dfrac{-7}{13}=\dfrac{1}{2}\\ x=\dfrac{1}{2}-\dfrac{-7}{13}\\ x=\dfrac{13}{26}+\dfrac{14}{26}\\ x=\dfrac{17}{26}\)
SN
1
N
11 tháng 8 2017
1.
a) \(\dfrac{5}{18}+\dfrac{4}{7}+\dfrac{13}{18}+\dfrac{3}{7}\)
\(=\left(\dfrac{5}{18}+\dfrac{13}{18}\right)+\left(\dfrac{4}{7}+\dfrac{3}{7}\right)\)
\(=1+1=2\)
b) \(\dfrac{4}{9}.\dfrac{5}{19}.\dfrac{9}{4}\)
\(=\left(\dfrac{4}{9}.\dfrac{9}{4}\right).\dfrac{5}{19}\)
\(=1.\dfrac{5}{19}=\dfrac{5}{19}\)
tik mik nha!!!
11 tháng 8 2017
2) \(\dfrac{4}{9}.\dfrac{5}{19}.\dfrac{9}{4} =(\dfrac{4}{9}.\dfrac{9}{4}).\dfrac{5}{19} =1.\dfrac{5}{19} =\dfrac{5}{19}\)
6 tháng 3 2022
\(a,\dfrac{11}{22}-\dfrac{3}{16}.\dfrac{8}{18}+\dfrac{1}{18}=\dfrac{1}{2}-\dfrac{1}{12}+\dfrac{1}{18}=\dfrac{18}{36}-\dfrac{3}{36}+\dfrac{2}{36}=\dfrac{17}{36}\)
\(b,\dfrac{5}{7}+\dfrac{3}{7}:4-\dfrac{8}{9}.\dfrac{-3}{4}=\dfrac{5}{7}+\dfrac{3}{7}.\dfrac{1}{4}-\dfrac{-2}{3}=\dfrac{5}{7}+\dfrac{3}{28}+\dfrac{2}{3}=\dfrac{60}{84}+\dfrac{9}{84}+\dfrac{56}{84}=\dfrac{125}{84}\)
6 tháng 3 2022
\(a,12.\dfrac{-7}{11}.\dfrac{5}{6}.\dfrac{22}{7}=\left(12.\dfrac{5}{6}\right)\left(\dfrac{-7}{11}.\dfrac{22}{7}\right)=10.\left(-2\right)=-20\\ b,\dfrac{-8}{15}.\dfrac{7}{9}.\dfrac{5}{8}.\left(-18\right)=\left(\dfrac{-8}{15}.\dfrac{5}{8}\right)\left[\dfrac{7}{9}.\left(-18\right)\right]=\dfrac{-1}{3}.\left(-14\right)=\dfrac{14}{3}\)
PT
6 tháng 3 2022
a) 12.−711.56.227= (12.56)(−711.227)= 10.(−2)= −20.
b) −815.79.58.(−18)= (−815.58)[79.(−18)]= −13.(−14)= 143.
\(\dfrac{2x+5}{9}=\dfrac{7}{18}=>\dfrac{9\cdot7}{18}=2x+5\)
\(2x+5=3.5\)
\(2x=3.5-5\)
\(2x=\left(-1.5\right)\)
\(x=\left(-1.5\right):2\)
\(x=-0.75\)
=> x = -0.75
~ HT ~
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