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

5

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

1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10 + 11 + 12 

= ( 1 + 12 ) + ( 2 + 11 ) + ( 3 + 10 ) + ( 4 + 9 ) + ( 5 + 8 ) + ( 6 + 7 ) 

=     13         +     13       +     13       +      13     +    13      + 13

=               13 x 6 

=                 78

sai thui

1+2+3+4+5+6+7+8+9+10+11+12

=(1+9)+(2+8)+(3+7)+(4+6)+(5+10)+(11+12)

=10+10+10+10+15+23

=10×4+15+23

=40+15+23

=55+23

=78

ủng hộ nha có gì sai sót mong bạn thông cảm cho !!!

1 + 2 + 3 + 4 +5 + 6 + 7 + 8 + 9 + 10 +11 + 12

= ( 12 + 8 ) + ( 11 + 9 ) + ( 7 + 3 ) + ( 6 + 4 ) + ( 10 + 2 + 3 ) + 1

Mình cũng không biết nữa !

giải chi tiết hộ mình nhé

\(3\times\dfrac{7}{10}+\dfrac{7}{10}\times5+2\times\dfrac{7}{10}\)

\(=\dfrac{7}{10}\times\left(3+5+2\right)\)

\(=\dfrac{7}{10}\times10\)

\(=\dfrac{70}{10}=7\)

giúp mình đi T.T

(9+1)+(8+2)+(7+3)+(6+4)+10+5

=10+10+10+10+10+5=45

9+3+2+1+7+8+5+10+6+4= (9+1)+(2+8)+(3+7)+(4+6)+5=10+10+10+10+5=10.4+5=40+5=45

(9+1)+(3+7)+(2+8)+(6+4)+10

=10+10+10+10+10

=50

Ta có: \(1\frac{4}{5}+2\frac{5}{7}+3\frac{4}{5}+4\frac{5}{7}\)

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

\(=\left(\frac{9}{5}+\frac{19}{5}\right)+\left(\frac{19}{7}+\frac{33}{7}\right)\)

\(=\frac{28}{5}+\frac{52}{7}=13\frac{1}{35}\)

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

=        \(4\frac{4}{5}\)           +       \(6\frac{5}{7}\)

=           \(\frac{24}{5}\)         +        \(\frac{47}{7}\)

=  ...... ( tính nốt nhé )

=(1+3)×4/5+(2+4)×5/7

=4×4/5+6×5/7

=16/5+30/7

=16×6/7

Bằng 20/7 nhé bạn!

Phân số và hỗn số đó các bạn giúp mình với

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

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

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

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