a) 19/23

b) -5/11

a) 8/3 x 2/5 x 3/8 x 10 x 19/92

= ( 8/3 x 3/8 ) x ( 2/5 x 10 ) x 19/92

=     1 x 4 x 19/92

=     4 x 19/92   =   76/92  =  19/23

b) N = 5/7 x 5/11 + 5/7 x 2/11 - 5/7 x 14/11

       = 5/7 x ( 5/11 + 2/11 - 14/11 )

       = 5/7 x ( -7/11 )

       =   -5/11

Ban Tran Nguyen Dam Nhien trinh bay cach giai duoc khong?

\(\frac{5+8+11+14+...+68+71}{2\times43+3\times43+43\times5+7}\).

Xét tử số: 5+ 8+ 11+ 14+...+ 68.

Có số các số hạng là:

( 68- 5): 3+ 1= 22

Tử số là:

 ( 68+ 5)x 22: 2= 803

Xét mẫu số: 2x 43+ 3x 43+ 43x 5+ 7=( 2+ 3+ 5)x 43+ 7= 10x 43+ 7= 430+ 7= 437.

=> \(\frac{5+8+11+14+...+68+71}{2\times43+3\times43+43\times5+7}\)= \(\frac{803}{437}\).

a= 7/5

b=28/63

c=5/8

d=4/15

\(a)\frac{3}{8}+\frac{2}{5}+\frac{5}{8}=\left(\frac{3}{8}+\frac{5}{8}\right)+\frac{2}{5}=1+\frac{2}{5}=\frac{7}{5}\)

\(b)\frac{5}{7}.\frac{2}{3}.\frac{14}{15}=\frac{5.2.14}{7.3.15}=\frac{4}{9}\)

\(c)\frac{3}{8}+\frac{2}{5}.\frac{5}{8}=\frac{3}{8}+\frac{1}{4}=\frac{3}{8}+\frac{2}{8}=\frac{5}{8}\)

\(d)\frac{11}{15}-\left(\frac{2}{3}-\frac{1}{5}\right)=\frac{11}{15}-\frac{7}{15}=\frac{4}{15}\)

~Học tốt~

\(a)\frac{3}{8}+\frac{2}{5}+\frac{5}{8}=\left(\frac{3}{8}+\frac{5}{8}\right)+\frac{2}{5}=1+\frac{2}{5}=\frac{7}{5}\)

\(b)\frac{5}{7}.\frac{2}{3}.\frac{14}{15}=\frac{5.2.14}{7.3.15}=\frac{4}{9}\)

\(c)\frac{3}{8}+\frac{2}{5}.\frac{5}{8}=\frac{3}{8}+\frac{1}{4}=\frac{3}{8}+\frac{2}{8}=\frac{5}{8}\)

\(d)\frac{11}{15}-\left(\frac{2}{3}-\frac{1}{5}\right)=\frac{11}{15}-\frac{7}{15}=\frac{4}{15}\)

~Học tốt~

a) \(\frac{3}{8}+\frac{2}{5}+\frac{5}{8}=\frac{3}{8}+\frac{5}{8}+\frac{2}{5}=\frac{3+5}{8}+\frac{2}{5}\)

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

b) \(\frac{5}{7}\times\frac{2}{3}\times\frac{14}{15}=\frac{5}{7}\times\frac{14}{15}\times\frac{2}{3}=\frac{5\times2\times7}{7\times3\times5}\times\frac{2}{3}\)

\(=\frac{2}{3}\times\frac{2}{3}=\frac{4}{9}\)

c) \(\frac{3}{8}+\frac{2}{5}\times\frac{5}{8}=\frac{3}{8}+\frac{2\times5}{5\times8}=\frac{3}{8}+\frac{2}{8}\)

\(=\frac{5}{8}\)

d) \(\frac{11}{15}-\left(\frac{2}{3}-\frac{1}{5}\right)=\frac{11}{15}-\frac{2}{3}+\frac{1}{5}=\frac{11}{15}-\frac{2\times5}{3\times5}+\frac{3\times1}{3\times5}\)

\(=\frac{11}{15}-\frac{10}{15}+\frac{3}{15}=\frac{11-10+3}{15}=\frac{4}{15}\)

\(\dfrac{14}{9}\) x \(\dfrac{11}{8}-\dfrac{3}{8}\) x \(\dfrac{14}{9}\)

\(=\dfrac{14}{9}\) x \(\left(\dfrac{11}{8}-\dfrac{3}{8}\right)\)

\(=\dfrac{14}{9}\) x \(\dfrac{8}{8}=\dfrac{14}{9}\) x \(1\)

\(=\dfrac{14}{9}\)

oa cảm ơn bạn nhé :3

14/9 × 11/8 - 3/8 × 14/9 

= 14/9 × ( 11/8 - 3/8 ) 

= 14/9 × 8/8 

= 14/9 - 1 

= 5/9

a) Bạn xem lại thừa số thứ 2. Mình nghĩ phải là 149 x 327327 - 149149x327 

b) Số số hạng là (2072 - 5) : 3 + 1 = 690 (số)

Tổng là (2072 + 5). 690 : 2 = 716565

a) Câu a hình như sai đề

b) Số lượng số hạng của tổng trên là :

            \(\left(2072-5\right):3+1=690\) ( số )

Tổng có giá trị là :

              \(\frac{\left(2072+5\right)\times690}{2}=716565\)

                      Đáp số : \(716565\)

\(a.\dfrac{1}{2}:3+x=\dfrac{14}{5}\)

\(\dfrac{1}{6}+x=\dfrac{14}{5}\)

\(=>x=\dfrac{79}{30}\)

\(b.\dfrac{8}{5}:x:\dfrac{7}{4}=\dfrac{11}{6}\)

\(\left(\dfrac{8}{5}\cdot\dfrac{4}{7}\right):x=\dfrac{11}{6}\)

\(\dfrac{32}{35}:x=\dfrac{11}{6}\)

\(x=\dfrac{192}{385}\)

\(c.\dfrac{24}{10}+x:\dfrac{3}{4}=\dfrac{11}{3}\)

\(x:\dfrac{3}{4}=\dfrac{11}{3}-\dfrac{24}{10}\)

\(x:\dfrac{3}{4}=\dfrac{38}{30}\)

\(=>x=\dfrac{19}{20}\)

\(a,\dfrac{1}{2}:3+x=\dfrac{14}{5}\\ \Leftrightarrow x+\dfrac{1}{6}=\dfrac{14}{5}\\ \Leftrightarrow x=\dfrac{79}{30}\\ b,\dfrac{8}{5}:x:\dfrac{7}{4}=\dfrac{11}{6}\\ \Leftrightarrow x=\dfrac{192}{385}\\ c,\dfrac{24}{10}+x:\dfrac{3}{4}=\dfrac{11}{3}\\ \Leftrightarrow\dfrac{4}{3}x=\dfrac{19}{15}\\ \Leftrightarrow x=\dfrac{19}{20}\)

a   1/6+x=14/5

     x=14/5-1/6

     x= 79/30

b    8/5:x=11/6*7/4

     8/5:x=77/24

     x=77/24:8/5

     x=385/192

c  x:3/4=11/3-24/10

  x:3/4=19/5

  x=19/5*3/4

  x=57/20

2: \(=\dfrac{-2}{75}+\dfrac{5}{39}=\dfrac{33}{325}\)

3: \(=\dfrac{6}{11}\left(\dfrac{4}{9}+\dfrac{5}{9}\right)=\dfrac{6}{11}\)

4: \(=\dfrac{7}{19}\left(\dfrac{5}{13}+\dfrac{8}{13}-1\right)=-2\cdot\dfrac{7}{19}=-\dfrac{14}{19}\)

5: \(=\dfrac{2}{7}\left(\dfrac{4}{23}-\dfrac{27}{23}+1\right)=0\)

6: \(=\dfrac{3}{8}\left(\dfrac{3}{7}+\dfrac{4}{7}\right)+\dfrac{11}{8}=\dfrac{3}{8}+\dfrac{11}{8}=\dfrac{14}{8}=\dfrac{7}{4}\)