3+8+6+8+528+35
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![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
Giải:
a) \(\left(-\dfrac{5}{28}+1,75+\dfrac{8}{35}\right):\left(\dfrac{-39}{20}\right)\)
\(=\left(-\dfrac{5}{28}+\dfrac{7}{4}+\dfrac{8}{35}\right):\left(\dfrac{-39}{20}\right)\)
\(=\left(\dfrac{11}{7}+\dfrac{8}{35}\right):\left(-\dfrac{39}{20}\right)\)
\(=\dfrac{9}{5}:\left(-\dfrac{39}{20}\right)\)
\(=\dfrac{9.\left(-20\right)}{5.39}\)
\(=\dfrac{3.\left(-4\right)}{1.13}\)
\(=\dfrac{-12}{13}\)
b) \(6\dfrac{5}{12}:2\dfrac{3}{4}+11\dfrac{1}{4}.\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)
\(=\dfrac{77}{22}:\dfrac{11}{4}+\dfrac{42}{4}.\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)
\(=\dfrac{77}{22}.\dfrac{4}{11}+\dfrac{42}{4}.\left(\dfrac{5}{15}+\dfrac{3}{15}\right)\)
\(=\dfrac{7}{3}+\dfrac{42}{4}.\dfrac{8}{15}\)
\(=\dfrac{7}{3}+\dfrac{14.2}{1.3}\)
\(=\dfrac{7}{3}+\dfrac{28}{3}\)
\(=\dfrac{35}{3}\)
c) \(70,5-528:\dfrac{15}{2}\)
\(=70,5-528.\dfrac{2}{15}\)
\(=70,5-\dfrac{1056}{15}\)
\(=70,5-70,4\)
\(=0,1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Hướng dẫn giải:
a) 232 x 4
= (230 + 2) x 4
= 230 x 4 + 2 x 4
= 920 + 8 = 928
b) 608 x 4
= (600 + 8) x 4
= 600 x 4 + 8 x 4
= 2400 + 32 = 2432
![](https://rs.olm.vn/images/avt/0.png?1311)
a) ? : 6 = 7 7 x 6 = 42 | ? : 4 = 32 32 x 4 = 128 | ? : 3 = 18 18 x 3 = 54 |
b) 24 : ? = 6 24 : 6 = 4 | 40 : ? = 5 40 : 5 = 8 | 28 : ? = 4 28 : 4 = 7 |
![](https://rs.olm.vn/images/avt/0.png?1311)
A) \(\frac{1}{2}\cdot\left(\frac{2}{9}+\frac{3}{7}-\frac{5}{27}\right)\)
\(=\frac{1}{2}\cdot\frac{1}{2}\)
\(=\frac{1}{4}\)
B) \(\left(\frac{-5}{28}+1.75+\frac{8}{35}\right):\left(-3\frac{9}{20}\right)\)
\(=\left(\frac{-5}{28}+\frac{7}{4}+\frac{8}{35}\right):\frac{-69}{20}\)
\(=\frac{14}{5}:\frac{-69}{20}\)
\(=\frac{-56}{69}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{5}{8}+\dfrac{5}{24}+\dfrac{5}{48}+...+\dfrac{5}{528}\)
\(=\dfrac{5}{2.4}+\dfrac{5}{4.6}+\dfrac{5}{6.8}+...+\dfrac{5}{22.24}\)
\(=\dfrac{5}{2}.\left(\dfrac{2}{2.4}+\dfrac{2}{4.6}+\dfrac{2}{6.8}+...+\dfrac{2}{22.24}\right)\)
\(=\dfrac{5}{2}.\left(\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{6}+\dfrac{1}{6}-...-\dfrac{1}{22}+\dfrac{1}{22}-\dfrac{1}{24}\right)\)
\(=\dfrac{5}{2}.\left(\dfrac{1}{2}-\dfrac{1}{24}\right)\)
\(=\dfrac{5}{2}.\dfrac{11}{24}\)
\(=\dfrac{55}{48}\).
58+524+548+...+552858+524+548+...+5528
A=52.4+54.6+56.8+...+522.24=52.4+54.6+56.8+...+522.24
=52.(22.4+24.6+26.8+...+222.24)=52.(22.4+24.6+26.8+...+222.24)
=52.(12−14+14−16+16−...−122+122−124)=52.(12−14+14−16+16−...−122+122−124)
=52.(12−124)=52.(12−124)
=52.1124=52.1124
=5548=5548.
vậy A = 5548
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\dfrac{3}{5}+\dfrac{7}{8}=\dfrac{3.8+7.5}{5.8}=\dfrac{24+35}{40}=\dfrac{59}{40}\\ 2+\dfrac{3}{4}=\dfrac{2.4+3}{4}=\dfrac{11}{4}\\ 1-\dfrac{3}{4}=\dfrac{4-3}{4}=\dfrac{1}{4}\\\dfrac{6}{8}+7=\dfrac{6+7.8}{8}=\dfrac{62}{8}=\dfrac{31}{4}\\ \dfrac{35}{9}-2=\dfrac{35-2.9}{9}=\dfrac{17}{9}\)
Giải thích : \(\left(.\right)\) dấu chấm này là dấu nhân nhé
![](https://rs.olm.vn/images/avt/0.png?1311)
a: \(=\left(\dfrac{3}{17}+\dfrac{14}{17}\right)+\left(\dfrac{-5}{13}-\dfrac{8}{13}\right)+\left(\dfrac{-18}{35}-\dfrac{17}{35}\right)\)
=1-1-1
=-1
b: \(=\dfrac{-3}{8}\left(\dfrac{1}{6}+\dfrac{5}{6}\right)+\dfrac{-5}{8}=\dfrac{-3}{8}-\dfrac{5}{8}=-1\)
c: \(=\dfrac{4}{4}\cdot\dfrac{5}{15}\cdot\dfrac{11}{11}=\dfrac{1}{3}\)
a)\(=\left(-\dfrac{5}{13}+\dfrac{-8}{13}\right)+\left(-\dfrac{18}{35}-\dfrac{17}{35}\right)+\left(\dfrac{3}{14}+\dfrac{14}{17}\right)=-1-1+1=-1\)
b)\(=\dfrac{-3}{8}.\left(\dfrac{1}{6}+\dfrac{5}{6}\right)-\dfrac{10}{16}=-\dfrac{3}{8}.1-\dfrac{10}{16}=-\dfrac{6}{16}-\dfrac{10}{16}=-\dfrac{16}{16}=-1\)
c)\(\dfrac{-4.5.11}{11.5.3.-4}=\dfrac{1}{3}\)
588 tk mình nhé
3+8+6+8+528+35=588