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\(\frac{21}{11}\cdot\frac{68}{63}\cdot\frac{22}{17}\)
\(=1\cdot\frac{4}{3}\cdot2\)
\(=\frac{8}{3}\)
\(\left(\frac{27}{25}-\frac{4}{9}\right)-\left(\frac{2}{25}+\frac{5}{9}\right)\)
\(=\frac{27}{25}-\frac{4}{9}-\frac{2}{25}-\frac{5}{9}\)
\(=\left(\frac{27}{25}-\frac{2}{25}\right)-\left(\frac{4}{9}+\frac{5}{9}\right)\)
\(=1-1\)
\(=0\)
\(\frac{22}{25}.\left(\frac{5}{11}-\frac{8}{9}\right)-\frac{8}{9}\left(\frac{27}{4}-\frac{22}{25}\right)\)
\(\frac{22}{25}.\left(\frac{5}{11}-\frac{8}{9}\right)-\frac{8}{9}.\left(\frac{27}{4}-\frac{22}{25}\right)=\frac{22}{25}.\frac{5}{11}-\frac{22}{25}.\frac{8}{9}-\frac{8}{9}.\frac{27}{4}+\frac{8}{9}.\frac{22}{25}=\frac{2}{5}-\frac{6}{1}=\frac{-28}{5}\)
\(\frac{21}{11}\times\frac{22}{17}\times\frac{68}{63}\)
=\(\frac{21}{1}\times\frac{2}{17}\times\frac{68}{63}\)
= 21 x \(\frac{8}{63}\)
=\(\frac{8}{3}\)
1: =-2/9(15/17+2/17)=-2/9
2: \(=\dfrac{-6}{3}+\dfrac{-21}{90}\)
=-2-7/30=-67/30
3: \(=\dfrac{3}{4}\cdot\dfrac{7}{5}+\dfrac{9}{7}\cdot\dfrac{3}{2}\)
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
1: =-2/9(15/17+2/17)=-2/9
2: =−63+−2190=−63+−2190
=-2-7/30=-67/30
3: =34⋅75+97⋅32=34⋅75+97⋅32
=21/20+27/14=417/140
4: =-25/13(5/19+14/19)=-25/13
5: =-7/5-45/21=-7/5-15/7=-124/35
a, 410. 230=220.230=250
b,925.274.813= 350.312.312=374
Tương tự các câu khác....
a, 410.230 = (22)10.230 = 220.230 = 250
b, 925.274.813 = (32)25.(33)4.(34)3 = 350.312.312 = 374
c, 2550.1255 = (52)50.(53)5 = 5100.515 = 5115
d, 643.48.164 = (26)3.(22)8.(24)4 = 218.216.216 = 250
e, 38 : 36 = 32
210 : 83 = 210 : (23)3 = 210 : 29 = 2
127 : 67 = (12 : 6)7 = 27
@Dương Tuyết Mai
\(\left(\frac{27}{25}-\frac{4}{9}\right)-\left(\frac{2}{25}-\frac{5}{9}\right)\)
\(=\frac{27}{25}-\frac{4}{9}-\frac{2}{25}+\frac{5}{9}\)
\(=\left(\frac{27}{25}-\frac{2}{25}\right)+\left(-\frac{4}{9}+\frac{5}{9}\right)\)
\(=\frac{25}{25}+\frac{1}{9}=1+\frac{1}{9}=\frac{9}{9}+\frac{1}{9}\)
\(=\frac{10}{9}\)