\(a,\dfrac{3}{2}\times\dfrac{4}{5}\times\dfrac{2}{3}\times\dfrac{15}{4}\\ =\dfrac{3\times4\times2\times15}{2\times5\times3\times4}\\ =\dfrac{3\times4\times2\times5\times3}{2\times5\times3\times4}\\ =3\)

\(b,\dfrac{6}{7}\times\dfrac{5}{8}\times\dfrac{7}{3}\times\dfrac{7}{6}\times\dfrac{8}{5}\\ =\dfrac{6\times5\times7\times7\times8}{7\times8\times3\times6\times5}\\ =\dfrac{7}{3}\)

a) \(\dfrac{3}{2}\times\dfrac{4}{5}\times\dfrac{2}{3}\times\dfrac{15}{4}\)

\(=\left(\dfrac{3}{2}\times\dfrac{2}{3}\right)\times\left(\dfrac{4}{5}\times\dfrac{15}{4}\right)\)

\(=1\times3\)

\(=3\)

b) \(\dfrac{6}{7}\times\dfrac{5}{8}\times\dfrac{7}{3}\times\dfrac{7}{6}\times\dfrac{8}{5}\)

\(=\left(\dfrac{6}{7}\times\dfrac{7}{6}\right)\times\left(\dfrac{5}{8}\times\dfrac{8}{5}\right)\times\dfrac{7}{3}\)

\(=1\times1\times\dfrac{7}{3}\)

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

Chúc bạn học tốt

`a, 3/4 + 1/2 xx 7/2`

`= 3/4 + 7/4`

`=10/4`

`=5/2`

`b, 6/15 - 1/3 : 5/3`

`= 6/15 - 1/3 xx 3/5`

`= 6/15 - 3/15`

`= 3/15`

`=1/5`

`c, x-4/9 = 3/7 : 9/4`

`=> x-4/9= 3/7 xx 4/9`

`=> x-4/9= 12/63`

`=> x-4/9=4/21`

`=> x= 4/21 +4/9`

`=>x= 40/63`

`d, 7/9 xx 3/5 -1/2=1/5`

`->` sao lại bằng có `x` ko vậy ạ?

`a,`

`3/4+1/2 \times 7/2=3/4+7/4=10/4=5/2`

`b,`

`6/15 - 1/3 \div 5/3=6/15-1/5=1/5`

`c,` Tìm x?

`x-4/9=3/7 \div 9/4`

`x-4/9=4/21`

`x=4/21+4/9`

`x=40/63`

`d, 7/9x \times 3/5-1/2=1/5`

`7/9x \times 3/5=1/5+1/2`

`7/9x \times 3/5=7/10`

`7/9x=7/10 \div 3/5`

`7/9x=7/6`

`x=7/6 \div 7/9=3/2`

\(\frac{2}{3}+\frac{3}{4}:\frac{6}{7}+\frac{1}{8}.\frac{4}{3}\)

=\(\frac{2}{3}+\frac{3}{4}.\frac{7}{6}+\frac{1}{8}.\frac{4}{3}\)

=\(\frac{2}{3}+\frac{7}{8}+\frac{1}{6}\)

=\(\left(\frac{2}{3}+\frac{1}{6}\right)+\frac{7}{8}\)

=\(\frac{5}{6}+\frac{7}{8}\)

=\(\frac{41}{24}\)

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Bạn ơi không gửi linh tinh nhé

2017 nhé

\(\frac{2}{3}+\frac{3}{4}:\frac{6}{7}+\frac{1}{8}\cdot\frac{4}{3}\)

\(=\frac{2}{3}+\frac{3}{4}\cdot\frac{7}{6}+\frac{1}{8}\cdot\frac{4}{3}\)

\(=\frac{2}{3}+\frac{21}{24}+\frac{4}{24}\)

\(=\frac{16}{24}+\frac{21}{24}+\frac{4}{24}\)

\(=\frac{37}{24}+\frac{4}{24}\)

\(=\frac{41}{24}\)

2/3 + 3/4 : 6/7 + 1/8 x 4/3 = 2/3 + 7/8 + 1/6

                                      = 16/24 + 21/24 + 4/24

                                      = 41/24

Tính giá trị biểu thức a x 12 + 2,1 x b + 5 với a = 19,36 và b = 7,9 ?

Đáp số: 

\(\dfrac{1}{2}\times\dfrac{1}{3}+\dfrac{3}{4}\)

\(=\dfrac{1}{6}+\dfrac{3}{4}\)

\(=\dfrac{2}{12}+\dfrac{9}{12}\)

\(=\dfrac{11}{12}\)

____________________________

\(\dfrac{3}{7}-\dfrac{2}{7}:\dfrac{2}{3}\)

\(=\dfrac{3}{7}-\dfrac{2}{7}\times\dfrac{3}{2}\)

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

\(=0\)

Chúc bạn học tốt

1/2 x 1/3 + 3/4 = 1/6 + 3/4 = 4/24 + 18/24 = 22/24 = 11/12
3/7 - 2/7 : 2/3 = 3/7 - 2/7 x 3/2 = 3/7 - 3/7 = 0