Bạn chưa đăng nhập. Vui lòng đăng nhập để hỏi bài

Những câu hỏi liên quan
ailafananime
Xem chi tiết
Mạnh Lê
4 tháng 5 2017 lúc 17:38

\(B=\frac{5}{2.1}+\frac{4}{1.11}+\frac{3}{11.2}+\frac{1}{2.15}+\frac{13}{15.4}\)

\(=\frac{B}{7}=\frac{5}{2.7}+\frac{4}{7.11}+\frac{3}{11.14}+\frac{1}{14.15}+\frac{13}{15.4}\)

\(=\frac{B}{7}=\frac{1}{2}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+...+\frac{1}{15}-\frac{1}{28}\)

\(=\frac{B}{7}=\frac{1}{2}-\frac{1}{28}\)

\(=\frac{B}{7}=\frac{13}{28}\)

\(=B=\frac{13}{28}.7\)

\(=B=\frac{13}{4}\)

nguyễn thảo hân
Xem chi tiết
Thắng Nguyễn
15 tháng 5 2016 lúc 17:38

\(B=7\left(\frac{5}{2.1}+\frac{4}{1.11}+...+\frac{13}{15.4}\right)\)

\(B=7\left(\frac{5}{2.7}+\frac{4}{7.11}+...+\frac{13}{15.28}\right)\)

\(B=7\left(\frac{1}{2}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+...+\frac{1}{15}-\frac{1}{28}\right)\)

\(B=7\left(\frac{1}{2}-\frac{1}{28}\right)\)

\(B=7\times\frac{13}{28}\)

\(B=\frac{13}{4}\)

Nguyễn Thảo Hân
Xem chi tiết
Nguyễn Huy Tú
23 tháng 5 2016 lúc 19:30

\(\frac{1}{7}\)B=\(\frac{5}{2.7.1}+\frac{4}{1.7.11}+\frac{3}{11.2.7}+\frac{1}{2.7.15}+\frac{13}{15.4.7}\)

\(\frac{1}{7}\)B=\(\frac{5}{2.7}+\frac{4}{7.11}+\frac{3}{11.14}+\frac{1}{14.15}+\frac{13}{15.28}\)

\(\frac{1}{7}B=\frac{1}{2}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+\frac{1}{14}-\frac{1}{15}+\frac{1}{15}-\frac{1}{28}\)

\(\frac{1}{7}B=\frac{1}{2}-\frac{1}{28}\)

\(\frac{1}{7}B=\frac{13}{28}\)

B=\(\frac{13}{28}:\frac{1}{7}\)

B=\(\frac{13}{4}\)

nguyenzuka
1 tháng 5 2019 lúc 15:02

1717B=52.7.1+41.7.11+311.2.7+12.7.15+1315.4.752.7.1+41.7.11+311.2.7+12.7.15+1315.4.7

1717B=52.7+47.11+311.14+114.15+1315.2852.7+47.11+311.14+114.15+1315.28

17B=12−17+17−111+111−114+114−115+115−12817B=12−17+17−111+111−114+114−115+115−128

17B=12−12817B=12−128

17B=132817B=1328

B=1328:171328:17

B=134

1717B=52.7.1+41.7.11+311.2.7+12.7.15+1315.4.752.7.1+41.7.11+311.2.7+12.7.15+1315.4.7

1717B=52.7+47.11+311.14+114.15+1315.2852.7+47.11+311.14+114.15+1315.28

17B=12−17+17−111+111−114+114−115+115−12817B=12−17+17−111+111−114+114−115+115−128

17B=12−12817B=12−128

17B=132817B=1328

B=1328:171328:17

B=134

1717B=52.7.1+41.7.11+311.2.7+12.7.15+1315.4.752.7.1+41.7.11+311.2.7+12.7.15+1315.4.7

1717B=52.7+47.11+311.14+114.15+1315.2852.7+47.11+311.14+114.15+1315.28

17B=12−17+17−111+111−114+114−115+115−12817B=12−17+17−111+111−114+114−115+115−128

17B=12−12817B=12−128

17B=132817B=1328

B=1328:171328:17

B=134

1717B=52.7.1+41.7.11+311.2.7+12.7.15+1315.4.752.7.1+41.7.11+311.2.7+12.7.15+1315.4.7

1717B=52.7+47.11+311.14+114.15+1315.2852.7+47.11+311.14+114.15+1315.28

17B=12−17+17−111+111−114+114−115+115−12817B=12−17+17−111+111−114+114−115+115−128

17B=12−12817B=12−128

17B=132817B=1328

B=1328:171328:17

B=134

1717B=52.7.1+41.7.11+311.2.7+12.7.15+1315.4.752.7.1+41.7.11+311.2.7+12.7.15+1315.4.7

1717B=52.7+47.11+311.14+114.15+1315.2852.7+47.11+311.14+114.15+1315.28

17B=12−17+17−111+111−114+114−115+115−12817B=12−17+17−111+111−114+114−115+115−128

17B=12−12817B=12−128

17B=132817B=1328

B=1328:171328:17

B=134

1717B=52.7.1+41.7.11+311.2.7+12.7.15+1315.4.752.7.1+41.7.11+311.2.7+12.7.15+1315.4.7

1717B=52.7+47.11+311.14+114.15+1315.2852.7+47.11+311.14+114.15+1315.28

17B=12−17+17−111+111−114+114−115+115−12817B=12−17+17−111+111−114+114−115+115−128

17B=12−12817B=12−128

17B=132817B=1328

B=1328:171328:17

B=134

1717B=52.7.1+41.7.11+311.2.7+12.7.15+1315.4.752.7.1+41.7.11+311.2.7+12.7.15+1315.4.7

1717B=52.7+47.11+311.14+114.15+1315.2852.7+47.11+311.14+114.15+1315.28

17B=12−17+17−111+111−114+114−115+115−12817B=12−17+17−111+111−114+114−115+115−128

17B=12−12817B=12−128

17B=132817B=1328

B=1328:171328:17

B=134

1717B=52.7.1+41.7.11+311.2.7+12.7.15+1315.4.752.7.1+41.7.11+311.2.7+12.7.15+1315.4.7

1717B=52.7+47.11+311.14+114.15+1315.2852.7+47.11+311.14+114.15+1315.28

17B=12−17+17−111+111−114+114−115+115−12817B=12−17+17−111+111−114+114−115+115−128

17B=12−12817B=12−128

17B=132817B=1328

B=1328:171328:17

B=134

Nguyễn Thảo Hân
Xem chi tiết
Tài Nguyễn Tuấn
15 tháng 5 2016 lúc 18:14

Ta có : 

\(B=\frac{5}{2\cdot1}+\frac{4}{1\cdot11}+\frac{3}{11\cdot2}+\frac{1}{2\cdot15}+\frac{13}{15\cdot4}\)

\(=>\frac{B}{7}=\frac{5}{2\cdot7}+\frac{4}{7\cdot11}+\frac{3}{11\cdot14}+\frac{1}{14\cdot15}+\frac{13}{15\cdot28}\)

\(=>\frac{B}{7}=\frac{1}{2}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+\frac{1}{14}-\frac{1}{15}+\frac{1}{15}-\frac{1}{28}\)

\(=>\frac{B}{7}=\frac{1}{2}-\frac{1}{28}=\frac{14}{28}-\frac{1}{28}=\frac{13}{28}\)

\(=>B=\frac{13}{28}\cdot7=\frac{13}{4}\)

Phạm Nguyễn Tất Đạt
15 tháng 5 2016 lúc 17:57

Khó wá

Phạm Nguyễn Tất Đạt
15 tháng 5 2016 lúc 18:19

Hay

Đỗ Hoàng Tùng
Xem chi tiết
Nguyễn Bá Đề
16 tháng 3 2016 lúc 12:53

mình không biết đâu nhé

mình mới học lớp 4 thôi

đáp số mình học lớp 4

Hồng Hải
16 tháng 3 2016 lúc 12:56

bn viết như phân số đi mk thấy bn viết như kia là ko đúng, viết như phân số xong mk giải cho

Trần Đức Tùng
5 tháng 10 2023 lúc 20:40

nói luôn là không bt giải đi bày đặt

 

tran viet
Xem chi tiết
Nguyễn Hải Minh
2 tháng 5 2021 lúc 16:13

Ta có

 \(\frac{1}{7}B=\frac{5}{2.7}+\frac{4}{7.11}+\frac{3}{11.14}+\frac{1}{14.15}+\frac{13}{15.28}\)

\(\Rightarrow\frac{1}{7}B=\frac{1}{2}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+\frac{1}{11}-\frac{1}{14}+\frac{1}{14}-\frac{1}{15}+\frac{1}{15}-\frac{1}{28}\)

\(\Rightarrow\frac{1}{7}B=\frac{1}{2}-\frac{1}{28}\)

\(\Rightarrow\frac{1}{7}B=\frac{13}{28}\)

\(\Rightarrow B=\frac{13}{4}\)

Khách vãng lai đã xóa
✦๖ۣۜAugųsť❦❄
2 tháng 5 2021 lúc 16:10

\(=\frac{5}{2.1}+\frac{4}{1.11}+\frac{3}{11.2}+\frac{1}{2.15}+\frac{13}{15.4}\)

B:7=\(\frac{5}{2.7}+\frac{4}{7.11}+\frac{3}{11.14}+\frac{1}{14.15}+\frac{13}{15.28}\)

B:7=\(\frac{1}{2}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+...+\frac{1}{15}-\frac{1}{28}\)

B:7=\(\frac{1}{2}-\frac{1}{28}\)=\(\frac{13}{28}\)=>B=\(\frac{13}{4}\)

Khách vãng lai đã xóa
Nguyen Phuong Uyen
Xem chi tiết
Ngô Thi Thanh Tâm
Xem chi tiết
Võ Đông Anh Tuấn
24 tháng 6 2016 lúc 12:58

\(B=\frac{5}{2.1}+\frac{4}{1.11}+\frac{3}{11.2}+\frac{1}{2.15}+\frac{13}{15.4}\)

\(\frac{B}{7}=\frac{5}{2.7}+\frac{4}{7.11}+\frac{3}{11.14}+\frac{1}{14.15}+\frac{13}{15.4}\)

\(\frac{B}{7}=\frac{1}{2}-\frac{1}{7}+\frac{1}{7}-\frac{1}{11}+\frac{1}{11}-...+\frac{1}{15}-\frac{1}{28}\)

\(\frac{B}{7}=\frac{1}{2}-\frac{1}{28}\)

\(\frac{B}{7}=\frac{13}{28}\)

\(B=\frac{13}{28}.7\)

\(B=\frac{13}{4}\)

Nguyễn Tất Nhật Nam
Xem chi tiết

Giải:

\(\dfrac{3}{2}+\dfrac{6}{8}+\dfrac{9}{28}+\dfrac{12}{77}+\dfrac{15}{176}\) 

\(=\dfrac{3}{1.2}+\dfrac{6}{2.4}+\dfrac{9}{4.7}+\dfrac{12}{7.11}+\dfrac{15}{11.16}\) 

\(=3.\left(\dfrac{1}{1.2}+\dfrac{2}{2.4}+\dfrac{3}{4.7}+\dfrac{4}{7.11}+\dfrac{5}{11.16}\right)\) 

\(=3.\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{16}\right)\) 

\(=3.\left(1-\dfrac{1}{16}\right)\) 

\(=3.\dfrac{15}{16}\) 

\(=\dfrac{45}{16}\)

๖ۣۜDũ๖ۣۜN๖ۣۜG
20 tháng 6 2021 lúc 13:08

Đặt A = \(\dfrac{3}{2}+\dfrac{6}{8}+\dfrac{9}{28}+\dfrac{12}{77}+\dfrac{15}{176}\)

\(3\left(\dfrac{1}{1\times2}+\dfrac{2}{2\times4}+\dfrac{3}{4\times7}+\dfrac{4}{7\times11}+\dfrac{5}{11\times16}\right)\)

\(3\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{16}\right)\)

\(3\left(1-\dfrac{1}{16}\right)=3\times\dfrac{15}{16}=\dfrac{45}{16}\)