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\(=\frac{4}{2x4}+\frac{4}{4x6}+\frac{4}{6x8}+...+\frac{4}{18x20}\)
\(=2\left(\frac{1}{2}-\frac{1}{4}+\frac{1}{4}-\frac{1}{6}+...+\frac{1}{18}-\frac{1}{20}\right)\)
\(=2x\left(\frac{1}{2}-\frac{1}{20}\right)\\ =2x\frac{9}{20}\\ =\frac{9}{10}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{10}{2000}:\frac{10}{2000}.\frac{4}{5}+\frac{1}{5}+20\%+80\%\)
=\(1.\frac{4}{5}+\frac{1}{5}+\frac{1}{5}+\frac{4}{5}\)
=\(\frac{4}{5}.2+\frac{1}{5}.2\)
=\(\frac{8}{5}+\frac{2}{5}\)
=\(\frac{10}{5}=2\)
=
![](https://rs.olm.vn/images/avt/0.png?1311)
\(A=\frac{4\cdot0,125\cdot20,2\cdot800\cdot0,25}{1,01\cdot75+0,26\cdot101-1,01}\)
\(=\frac{4\cdot0,25\cdot0,125\cdot800\cdot20,2}{1,01\cdot75+0,26\cdot100\cdot1,01-1,01}\)
\(=\frac{1\cdot100\cdot20,2}{1,01\cdot\left(75+26-1\right)}\)
\(=\frac{100\cdot20,2}{100\cdot1,01}\)
= 20
\(B=\left(\frac{178}{179}+\frac{179}{180}+\frac{180}{181}\right)\cdot\left(\frac{80}{56}-\frac{15}{12}:\frac{7}{8}\right)\)
\(=\left(\frac{178}{179}+\frac{179}{180}+\frac{180}{181}\right)\cdot\left(\frac{10}{7}-\frac{5}{4}\cdot\frac{8}{7}\right)\)
\(=\left(\frac{178}{179}+\frac{179}{180}+\frac{180}{181}\right)\cdot\left(\frac{10}{7}-\frac{10}{7}\right)\)
\(=\left(\frac{178}{179}+\frac{179}{180}+\frac{180}{181}\right)\cdot0\)
= 0
![](https://rs.olm.vn/images/avt/0.png?1311)
a) \(\frac{3}{5}+25-\frac{1}{5}=\left(\frac{3}{5}-\frac{1}{5}\right)+25=\frac{2}{5}+25=\frac{2}{5}+\frac{125}{5}=\frac{127}{5}\)
b) \(13\times3\times32,27+67,63\times39=39\times32,27+67,63\times39\)
\(=39\times\left(32,27+67,63\right)\)
\(=39\times99,9=3196,8\)
(Bạn xem lại đề nhé)
c) \(\left(1-\frac{1}{2}\right)\times\left(1-\frac{1}{3}\right)\times\left(1-\frac{1}{4}\right)\times....\times\left(1-\frac{1}{100}\right)\)
\(=\frac{1}{2}\times\frac{2}{3}\times\frac{3}{4}\times.....\times\frac{99}{100}\)
\(=\frac{1\times2\times3\times...\times99}{2\times3\times4\times....\times100}=\frac{1}{100}\)
a, \(\frac{3}{5}+25-\frac{1}{5}=\frac{127}{5}\)
b, \(\text{13 x 3 x 32,27 + 67,63 x 39 =}3896,1\)
............................
thank for watching me do homework
0,8 : [ \(\frac{4}{35}\)x 1,25 x ( 108% - \(\frac{2}{5}\)) : \(\frac{1}{2}\)]
Lm nhanh kết bạn tk nhá
![](https://rs.olm.vn/images/avt/0.png?1311)
=4/5:[4/35x5/4x(27/25-2/5):1/2]
=4/5:[1/7x17/25:1/2]
=4/5:[17/175:1/2]
=4/5:34/175
=4/5x175/34
=70/17
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\frac{2}{5}\)x \(\frac{3}{7}\)x\(\frac{2}{5}\)x\(\frac{4}{7}\)
=\(\frac{2}{5}\)x ( \(\frac{3}{7}+\frac{4}{7}\))
=\(\frac{2}{5}\)x\(1\)
=\(\frac{2}{5}\)
\({4 \over 5} \), 80% và 0,8 đều có chung giá trị. Do đó có chung giá trị nên có thể đặt ra bên ngoài luôn:
=0.8x(27+24+1+48) =0.8*100=80
giúp mik zới ai đúng mik k nhé