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4 tháng 6 2017

Ta có ; \(\frac{3}{7}\times\frac{4}{11}+\frac{3}{7}\times\frac{5}{11}+\frac{1}{2}\)

\(=\frac{3}{7}\times\left(\frac{4}{11}+\frac{5}{11}\right)+\frac{1}{2}\)

\(=\frac{3}{7}\times\frac{9}{11}+\frac{1}{2}\)

\(=\frac{27}{77}+\frac{1}{2}\)

\(=\frac{131}{154}\)

4 tháng 6 2017

\(\frac{3}{7}\times\left(\frac{4}{11}+\frac{5}{11}\right)+\frac{1}{2}\)

\(=\frac{3}{7}\times\frac{9}{11}+\frac{1}{2}\)

\(=\frac{27}{77}+\frac{1}{2}\)

\(=\frac{131}{154}\)

8 tháng 4 2017

minh ko biet nua moi lop 4 thoi

22 tháng 10 2017

a, 6/9+5/7+1/3=2/3+5/7+1/3=5/7+1=12/7

b, 17/7+6/5-20/14=17/7+6/5-10/7=6/5+1=11/5

c,2/5x1/4+3/4x2/5=2/5x(1/4+3/4)=2/5x1=2/5

d, 6/11:4/6+5/11:2/3=6/11:2/3+5/11:2/3=(6/11+5/11):2/3=3/2

nha

13 tháng 9 2017

a) \(\frac{11}{15}+\frac{5}{7}+\frac{2}{7}+\frac{4}{15}=\left(\frac{11}{15}+\frac{4}{15}\right)+\left(\frac{5}{7}+\frac{2}{7}\right)\)

\(=2\)

b) \(\frac{5}{9}\times\frac{1}{2}\times\frac{5}{9}\times\frac{6}{4}=\frac{25}{81}\times\frac{3}{4}=\frac{25}{108}\)

c) \(\frac{7}{8}\div\frac{1}{2}+\frac{9}{8}\div\frac{1}{2}=\left(\frac{7}{8}+\frac{9}{8}\right)\div\frac{1}{2}\)

\(=2\div\frac{1}{2}=4\)

d) \(\frac{17}{10}+\frac{1}{2}-\frac{7}{10}=\left(\frac{17}{10}-\frac{7}{10}\right)+\frac{1}{2}\)

\(=1+\frac{1}{2}=\frac{3}{2}\)

13 tháng 9 2017

a) \(\frac{11}{15}+\frac{5}{7}+\frac{2}{7}+\frac{4}{15}\)

\(=\left(\frac{11}{15}+\frac{4}{15}\right)+\left(\frac{5}{7}+\frac{2}{7}\right)\)

\(=1+1\)

\(=2\)

b) \(\frac{5}{9}.\frac{1}{2}.\frac{5}{9}.\frac{6}{4}\)

\(=\left(\frac{5}{9}\right)^2\left(\frac{1}{2}.\frac{6}{4}\right)\)

\(=\frac{25}{81}.\frac{3}{4}\)

\(=\frac{25}{108}\)

c) \(\frac{7}{8}:\frac{1}{2}+\frac{9}{8}:\frac{1}{2}\)

\(=\frac{7}{8}.2+\frac{9}{8}.2\)

\(=2\left(\frac{7}{8}+\frac{9}{8}\right)\)

\(=2.\frac{16}{8}\)

\(=2.2\)

\(=4\)

d) \(\frac{17}{10}+\frac{1}{2}-\frac{7}{10}\)

\(=\left(\frac{17}{10}-\frac{7}{10}\right)+\frac{1}{2}\)

\(=1+\frac{1}{2}\)

\(=\frac{2}{2}+\frac{1}{2}\)

\(=\frac{3}{2}\)

13 tháng 9 2017

a,(11/15+4/15)+(5/7+2/7)

=1+1

=2

b,5/9x(1/2+6/4)

=5/9x2

=10/9

c,1/2:(7/8+9/8)

=1/2:2

=1

d,(17/10-7/10)+1/2

=1+1/2

=3/2

13 tháng 9 2017

a ) (11/15+4/15 ) + ( 5/7 +2 /7 )

=1+1

= 2

b)5/9 x ( 1/ 2 + 6/ 4 )

= 5/9 x 2

=10/9 

c) 17/10-5/10-7/10

=(17-5-7) / 10

= 5/10

19 tháng 4 2018

C1 :   \(\frac{7}{11}\):\(\frac{3}{5}\)+\(\frac{4}{11}\):\(\frac{3}{5}\)

=\(\frac{7}{11}\)x\(\frac{5}{3}\)+\(\frac{4}{11}\)x\(\frac{5}{3}\)

=\(\frac{35}{33}\)+\(\frac{20}{33}\)

=\(\frac{55}{33}\)=\(\frac{5}{3}\)

C2:  \(\frac{7}{11}\):\(\frac{3}{5}\)+\(\frac{4}{11}\):\(\frac{3}{5}\)

\(\frac{3}{5}\)x (\(\frac{7}{11}\)+\(\frac{4}{11}\))

=\(\frac{3}{5}\)x 1= \(\frac{3}{5}\)

19 tháng 4 2018

\(C1:\frac{7}{11}:\frac{3}{5}+\frac{4}{11}:\frac{3}{5}\)

\(=\frac{7}{11}x\frac{5}{3}+\frac{4}{11}x\frac{5}{3}\)

\(=\frac{35}{33}+\frac{20}{33}\)

\(=\frac{55}{33}=\frac{5}{3}\)

\(C2:\frac{7}{11}:\frac{3}{5}+\frac{4}{11}:\frac{3}{5}\)

\(=\frac{7}{11}x\frac{5}{3}+\frac{4}{11}x\frac{5}{3}\)

\(=\frac{5}{3}x\left(\frac{7}{11}+\frac{4}{11}\right)\)

\(=\frac{5}{3}x1=\frac{5}{3}\)