1.

\(a,\frac{1}{7}+\frac{3}{4}+\frac{2}{7}+\frac{4}{7}=\frac{1}{7}+\frac{2}{7}+\frac{4}{7}+\frac{3}{4}\)

\(=1+\frac{3}{4}=\frac{7}{4}.\)

\(b,\frac{4}{7}:\frac{2}{5}+\frac{3}{7}:\frac{2}{5}-\frac{7}{9}=\left(\frac{4}{7}+\frac{3}{7}\right):\frac{2}{5}-\frac{7}{9}\)

\(=1:\frac{2}{5}-\frac{7}{9}=\frac{5}{2}-\frac{7}{9}\)

\(=\frac{31}{18}.\)

a)3/4+(1/7+2/7+4/7)

=3/4+1

=7/4

b)2/5:(4/7+3/7)-7/9

=2/5:1-7/9

=2/5-7/9

=-17/45

31/18

\(\frac{3}{4}x\frac{4}{5}:\frac{3}{5}x\frac{6}{7}:\frac{1}{7}x\frac{5}{6}\)\(=\)\(\frac{3}{4}x\frac{4}{5}x\frac{5}{3}x\frac{6}{7}x\frac{7}{1}x\frac{5}{6}\)\(=\)\(\frac{3x4x5x6x7x5}{4x5x3x7x1x6}\)\(=\)\(\frac{\left(3\right)x\left(4\right)x\left(5\right)x\left(6\right)x\left(7\right)x5}{\left(3\right)x\left(4\right)x\left(5\right)x\left(6\right)x\left(7\right)x1}\)\(=\)\(\frac{5}{1}\)\(=\)\(5\).

5

3/4 x 4/5 : 3/5 x 6/7 : 1/7 x 5/6

= 3/4 x 4/5 x 5/3 x 6/7 x7/1 x 5/6

= 5

Bằng 20/7 nhé bạn!

Phân số và hỗn số đó các bạn giúp mình với

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

\(=\frac{3}{7}\times\left(\frac{1}{5}+\frac{4}{5}\right)+\frac{17}{7}\)

\(=\frac{3}{7}+\frac{17}{7}\)

\(=\frac{20}{7}\)

\(\dfrac{3}{5}\times\dfrac{2}{7}-\dfrac{3}{5}\times\dfrac{4}{7} +\dfrac{3}{5}\)

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

\(=\dfrac{3}{5}\times\left(\dfrac{7}{7}+\dfrac{2}{7}-\dfrac{4}{7}\right)\)

\(=\dfrac{3}{5}\times\left(\dfrac{7+2-4}{7}\right)\)

\(=\dfrac{3}{5}\times\dfrac{5}{7}\)

\(=\dfrac{3}{7}\)

= 3/5 x 2/7 - 3/5 x 4/7 + 3/5 x 1

= 3/5 x ( 2/7 + 4/7 + 1 )

= 3/5 x 1

= 3/5

nhớ tích nha

3/4 x 4/5 x 5/6 x 6/7

= 3/5 x 5/6 x 6/7 

= 1/2 x 6/7 

= 3/7

cảm ơn bạn nhé