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16 tháng 4 2017
a) 2763 + 152 = 2915;
b) (-7) + (-14) = -21;
c) (-35) + (-9) = -44.
9 tháng 4 2018
a,\(\dfrac{3}{7}\).\(\dfrac{14}{5}\)=\(\dfrac{6}{5}\)
b,\(\dfrac{35}{9}\).\(\dfrac{81}{7}\)=45
c,\(\dfrac{28}{17}\).\(\dfrac{68}{14}\)=8
d,\(\dfrac{35}{46}\).\(\dfrac{23}{105}\)=\(\dfrac{1}{6}\)
e,\(\dfrac{12}{5}\):\(\dfrac{16}{15}\)=\(\dfrac{12}{5}\).\(\dfrac{15}{16}\)=\(\dfrac{9}{4}\)
i,\(\dfrac{9}{8}\):\(\dfrac{6}{5}\)=\(\dfrac{9}{8}\).\(\dfrac{5}{6}\)=\(\dfrac{15}{16}\)
PA
31 tháng 5 2016
c.
\(\frac{1}{3}\times\frac{5}{7}-\frac{7}{27}\times\frac{36}{14}\)
\(=\frac{1}{3}\times\frac{5}{7}-\frac{7}{3\times9}\times\frac{4\times9}{7\times2}\)
\(=\frac{1}{3}\times\frac{5}{7}-\frac{1}{3}\times\frac{4}{6}\)
\(=\frac{1}{3}\times\left(\frac{5}{7}-\frac{4}{6}\right)\)
\(=\frac{1}{3}\times\left(\frac{30-38}{42}\right)\)
\(=\frac{1}{3}\times\frac{-8}{42}\)
\(=-\frac{4}{63}\)
Chúc bạn học tốt
11 tháng 4 2017
a )
\(\frac{2}{7}+\frac{7}{7}.\frac{14}{25}\)
\(=\frac{2}{7}+1.\frac{14}{25}=\frac{2}{7}+\frac{14}{25}\)
\(=\frac{50}{175}+\frac{98}{175}=\frac{148}{175}\)
b)
\(\frac{6}{7}+\frac{5}{7}:5-\frac{8}{9}\)
\(=\frac{6}{7}+\frac{5}{30}-\frac{8}{9}\)
\(=\frac{6}{7}+\frac{1}{6}-\frac{8}{9}\)
\(=\frac{36}{42}+\frac{7}{42}-\frac{8}{9}\)
\(=\frac{43}{42}-\frac{8}{9}=\frac{129}{126}-\frac{112}{126}=\frac{17}{126}\)
tk ủng hộ mk nha!!!!!!!!
HP
29 tháng 4 2018
\(a,\)\(\frac{1}{2}.\left(\frac{2}{9}+\frac{3}{7}-\frac{5}{37}\right)\)
\(\Rightarrow\frac{1}{2}.\left(\frac{2.259}{2331}+\frac{3.333}{2331}-\frac{5.63}{2331}\right)\)
\(\Rightarrow\frac{1}{2}.\left(\frac{518}{2331}+\frac{999}{2331}-\frac{315}{2331}\right)\)
\(\Rightarrow\frac{1}{2}.\left(\frac{518+999-315}{2331}\right)\)
\(\Rightarrow\frac{1}{2}.\frac{1202}{2331}\)
\(\Rightarrow\frac{601}{2331}\)
HP
29 tháng 4 2018
\(b,\)\(\left(-\frac{5}{28}+1,75+\frac{8}{35}\right):\left(-3\frac{9}{20}\right)\)
\(\Rightarrow\frac{9}{5}:\left(-\frac{69}{20}\right)\)
\(=-\frac{12}{23}\)
\(c,\)\(\frac{1}{3}.\frac{1}{5}-\frac{7}{27}.\frac{36}{14}\)
\(=\frac{1}{15}-\frac{2}{3}\)
\(=\frac{1}{15}-\frac{10}{15}=-\frac{9}{15}=-\frac{3}{5}\)
\(d,\)\(70,5-528:\frac{15}{2}\)
\(=70,5-\frac{352}{5}\)
\(=\frac{1}{10}\)
10 tháng 6 2016
A = 1/2 + 1/14 + 1/35 +1/65 + 1/104 + 1/152 => 1/2 A = 1/4 + 1/28 + 1/70 + ........+ 1/304 = 1/4x1 + 1/4x7 + 1/7x10 + ............ + 1/16x19 = 1/3 ( 3/1x4 + 3/4x7 + ...+ 3/16x19 ) = 1/3 ( 1 - 1/4 + 1/4 - 1/7 + .....+1/16 - 1/19 = 1/3 x ( 1 - 1/19 ) = 1/3 x 18/19 = 6/19 => A = 6/19 : 1/2 = 12/19 _ _
10 tháng 6 2016
C= 1/2 + 1/14 + 1/35+1/65+1/104+1/152 = 12/19 nhé bn
KZ
25 tháng 7 2021
a, 3 \(\frac{14}{19}\)+ \(\frac{13}{17}\)+ \(\frac{35}{43}\)+ 6\(\frac{5}{19}\)+ \(\frac{8}{43}\)= \(\left(3\frac{14}{19}+6\frac{5}{19}\right)+\left(\frac{35}{43}+\frac{8}{43}\right)+\frac{13}{17}=\)\(9+1+\frac{13}{17}=8+\frac{13}{17}=8\frac{13}{17}\)
b, \(\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{11}+1\frac{5}{7}\)\(=\frac{-5}{7}\left(\frac{2}{11}+\frac{9}{11}\right)+1\frac{5}{7}\)\(=\frac{-5}{7}.1+1\frac{5}{7}\)\(=\frac{-5}{7}+\frac{12}{7}=\frac{7}{7}=1\)
Chúc bn học tốt
30 tháng 7 2021
\(3\frac{14}{19}+\frac{13}{17}+\frac{35}{43}+6\frac{5}{19}+\frac{8}{43}\)
\(=\left(3\frac{14}{19}+6\frac{5}{19}\right)+\left(\frac{35}{43}+\frac{8}{43}\right)+\frac{13}{17}\)
\(=10+1+\frac{13}{17}=11+\frac{13}{17}=11\frac{13}{17}\)
DM
6
17 tháng 3 2018
\(\dfrac{-14}{21};\dfrac{-2}{15};\dfrac{14}{-35}\)
\(\dfrac{-17}{21}=\dfrac{-85}{105}\);\(\dfrac{-2}{15}=\dfrac{-14}{105};\dfrac{14}{-35}=\dfrac{-14}{35}=\dfrac{-42}{105}\)
\(\dfrac{17}{60};\dfrac{5}{12};\dfrac{64}{90}\)
\(\dfrac{17}{60}=\dfrac{51}{180};\dfrac{-5}{12}=\dfrac{-75}{180};\dfrac{-64}{90}=\dfrac{-32}{45}=\dfrac{-128}{180}\)
bài2:
a)\(\dfrac{3}{5}>\dfrac{4}{7}\)
b)\(\dfrac{-5}{8}< \dfrac{-7}{12}\)
c)\(\dfrac{5}{-3}< \dfrac{-9}{12}\)
a) 2763 + 152 = 2915
b) Ta có : |–7| = 7; |–14| = 14.
Do đó: (–7) + (–14) = – ( |–7| + |–14| ) = – (7 + 14) = –21.
c) (–35) + (–9) = – (|–35| + |–9|) = – (35 + 9) = –44.