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a. 215 - 5 + 10 = 210 + 10 = 220
b. 13 + (-17) = -4
c. 25 . 5 . 2014 . 4 . 2 = (25 . 4) . (5 . 2) . 2014 = 100 . 10 . 2014 = 1000 . 2014 = 2014000
đ. 24.35 + 76.35 - 500 = (24 + 76) . 35 - 500 = 100 . 35 - 500 = 3500 - 500 = 3000
e. 3 + 7 + 11 + 15 + ... + 399 + 403 = 406 . 101 : 2 = 20503
\(a,\frac{-1}{9}.\frac{15}{22}.\frac{-9}{25}\)
\(=\frac{-1.15.\left(-9\right)}{9.22.25}\)
\(=\frac{3}{110}\)
\(b,\frac{-2}{7}.\left(\frac{5}{13}-\frac{9}{15}\right)-\frac{2}{7}.\frac{8}{13}\)
\(=\frac{-2}{7}.\left(\frac{5}{13}+\frac{8}{13}-\frac{3}{5}\right)\)
\(=\frac{-2}{7}.\left(1-\frac{3}{5}\right)\)
\(=\frac{-2}{7}.\frac{2}{5}\)
\(=\frac{-4}{35}\)
\(c,\frac{3}{10}.\left(\frac{-4}{9}+\frac{2}{5}\right)-\frac{3}{10}.\left(\frac{5}{9}-\frac{3}{5}\right)\)
\(=\frac{3}{10}.\left[\left(\frac{-4}{9}+\frac{2}{5}\right)-\left(\frac{5}{9}-\frac{3}{5}\right)\right]\)
\(=\frac{3}{10}.\left(\frac{-4}{9}+\frac{2}{5}-\frac{5}{9}+\frac{3}{5}\right)\)
\(=\frac{3}{10}.\left[\left(\frac{-4}{9}-\frac{5}{9}\right)+\left(\frac{2}{5}+\frac{3}{5}\right)\right]\)
\(=\frac{3}{10}.\left(-1+1\right)\)
\(=\frac{3}{10}.0\)
\(=0\)
\(d,\frac{4}{11}-\frac{5}{13}+\frac{7}{11}-\frac{8}{13}\)
\(=\left(\frac{4}{11}+\frac{7}{11}\right)+\left(\frac{-5}{13}-\frac{8}{13}\right)\)
\(=1-1\)
\(=0\)
Học tốt
a)-4/11+5/6+7/11-5/6
b)-5/6.7/13+19/13.6/-5+2/5
c)3/7.(-0,5+3/2)-2/7:25%
mọi người giúp e vs ạ
e cần gấp
a; - \(\dfrac{4}{11}\) + \(\dfrac{5}{6}\) + \(\dfrac{7}{11}\) - \(\dfrac{5}{6}\)
= (-\(\dfrac{4}{11}\) + \(\dfrac{7}{11}\)) + (\(\dfrac{5}{6}\) - \(\dfrac{5}{6}\))
= - \(\dfrac{3}{11}\) + 0
= - \(\dfrac{3}{11}\)
b; -\(\dfrac{5}{6}\).\(\dfrac{7}{13}\) + \(\dfrac{19}{13}\).\(\dfrac{6}{-5}\) + \(\dfrac{2}{5}\)
= - \(\dfrac{35}{78}\) - \(\dfrac{114}{65}\) + \(\dfrac{2}{5}\)
= - \(\dfrac{859}{390}\) + \(\dfrac{2}{5}\)
= - \(\dfrac{703}{390}\)
Dễ thế cũng hỏi ở trường tính hay lắm mà:
a) \(\dfrac{3}{7}.\dfrac{8}{11}+\dfrac{3}{7}.\dfrac{5}{11}-\dfrac{3}{7}.\dfrac{2}{11}\)
\(=\dfrac{3}{7}.\left(\dfrac{8}{11}+\dfrac{5}{11}-\dfrac{2}{11}\right)\)
\(=\dfrac{3}{7}.\left(\dfrac{8+5-2}{11}\right)=\dfrac{3}{7}.\dfrac{11}{11}=\dfrac{3}{7}\)
b) \(\dfrac{3}{13}.\dfrac{8}{25}+\dfrac{3}{13}.\dfrac{11}{25}+\dfrac{3}{13}.\dfrac{6}{25}-\dfrac{3}{13}\)
\(=\dfrac{3}{13}.\left(\dfrac{8}{25}+\dfrac{11}{25}+\dfrac{6}{25}-1\right)\)
\(=\dfrac{3}{13}.\left(\dfrac{8+11+6}{25}-1=\right)\dfrac{3}{13}.0=0\)
a,
\(\dfrac{3}{7}.\dfrac{8}{11}+\dfrac{3}{7}.\dfrac{5}{11}-\dfrac{3}{7}.\dfrac{2}{11}=\dfrac{3}{7}\left(\dfrac{8}{11}+\dfrac{5}{11}-\dfrac{2}{11}\right)=\dfrac{3}{7}.1=\dfrac{3}{7}\)
b,
\(\dfrac{3}{13}.\dfrac{8}{25}+\dfrac{3}{13}.\dfrac{11}{25}+\dfrac{3}{13}.\dfrac{6}{25}-\dfrac{3}{13}=\dfrac{3}{13}\left(\dfrac{8}{25}+\dfrac{11}{25}+\dfrac{6}{25}-1\right)=\dfrac{3}{13}.0=0\)