\(\frac{1}{4}\)+\(\frac{2}{5}\)+\(\frac{...">
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7 tháng 8 2017

1/4 + 2/5 + 6/8 + 9/15 + 6/7 = ( 1/4 + 6/8 ) +  ( 2/5 + 9/15 ) + 6/7

                                            = 1 + 1 + 6/7

                                            = 2 + 6/7 

                                            = 20/7

\(\frac{1}{4}+\frac{2}{5}+\frac{6}{8}+\frac{9}{15}+\frac{6}{7}\)

\(\left(\frac{1}{4}+\frac{6}{8}\right)+\left(\frac{2}{5}+\frac{9}{15}\right)+\frac{6}{7}\)

\(1+1+\frac{6}{7}\)

= 2 + \(\frac{6}{7}\)

\(\frac{14}{7}+\frac{6}{7}=\frac{20}{7}\)

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

\(=2\)

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

= 5/9 x 2

=10/9 

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

=(17-5-7) / 10

= 5/10

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

7 tháng 8 2017

\(\frac{10}{18}+\frac{4}{9}+\frac{26}{10}+\frac{12}{5}+\frac{9}{15}\)

\(=\frac{5}{9}+\frac{4}{9}+\frac{13}{5}+\frac{12}{5}+\frac{3}{5}\)

\(=\left(\frac{5}{9}+\frac{4}{9}\right)+\left(\frac{13}{5}+\frac{12}{5}+\frac{3}{5}\right)\)

\(=1+\frac{28}{5}\)

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

7 tháng 8 2017

Ta có:

a) \(\frac{10}{18}+\frac{4}{9}+\frac{26}{10}+\frac{12}{5}+\frac{9}{15}=\frac{5}{9}+\frac{4}{9}+\frac{13}{5}+\frac{12}{5}+\frac{9}{15}=1+1+\frac{9}{15}=1\frac{9}{15}\)

b)\(\frac{10}{18}+\frac{4}{9}+\frac{1}{8}+\frac{1}{16}+\frac{1}{32}+\frac{1}{64}+\frac{1}{128}=\left(\frac{5}{9}+\frac{4}{9}\right)+\left(\frac{16}{128}+\frac{8}{128}+\frac{4}{128}+\frac{2}{128}+\frac{1}{128}\right)\)

\(=1+\frac{31}{128}=1\frac{31}{128}\)

30 tháng 7 2018

\(\frac{23}{12}\)

\(\frac{314}{105}\)

\(\frac{59}{60}\)

\(\frac{199}{90}\)

\(\frac{1}{18}\)

\(\frac{13}{36}\)

\(\frac{4}{221}\)

\(\frac{4}{85}\)

30 tháng 7 2018

phải giải thích đày đủ

22 tháng 7 2018

Dùng máy tính đấy em ơi

7 tháng 3 2020

a, 6/8;4/7

b,96/48;10/42

7 tháng 3 2020

\(\frac{6}{8}+\frac{4}{8}=\frac{6+4}{8}=\frac{10}{8}=\frac{5}{4}\)

\(\frac{5}{7}-\frac{1}{7}=\frac{5-1}{7}=\frac{4}{7}\)

\(\frac{9}{6}+\frac{4}{8}=\frac{9\times3}{6\times3}+\frac{4\times2}{8\times2}=\frac{27}{19}+\frac{8}{19}=\frac{35}{19}\)

\(\frac{5}{7}-\frac{4}{6}=\frac{5\times6}{7\times6}-\frac{4\times7}{6\times7}=\frac{30}{42}-\frac{28}{42}=\frac{2}{42}=\frac{1}{21}\)

\(\frac{6}{8}+\frac{4}{8}=\frac{6+4}{8}=\frac{10}{8}=\frac{5}{4}\)