4 tạ 1 yến, 7 tấn, 39 yến nha :>

Minhg không biết

\(\frac{7}{1.5}+\frac{7}{5.9}+\frac{7}{9.13}+\frac{7}{13.17}+\frac{7}{17.21}\)

\(=\frac{7}{4}.\left(\frac{4}{1.5}+\frac{4}{5.9}+\frac{4}{9.13}+\frac{4}{13.17}+\frac{4}{17.21}\right)\)

\(=\frac{7}{4}.\left(1-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+\frac{1}{13}-\frac{1}{17}+\frac{1}{17}-\frac{1}{21}\right)\)

\(=\frac{7}{4}.\left(1-\frac{1}{21}\right)\)

\(=\frac{7}{4}.\frac{20}{21}=\frac{7.4.5}{4.7.3}\)

\(=\frac{5}{3}\)

~ Rất vui vì giúp đc bn ~

Bài giải

\(\frac{7}{1\cdot5}+\frac{7}{5\cdot9}+\frac{7}{9\cdot13}+\frac{7}{13\cdot17}+\frac{7}{17\cdot21}\)

\(=\frac{7}{4}\left(\frac{4}{1\cdot5}+\frac{4}{5\cdot9}+\frac{4}{9\cdot13}+\frac{4}{13\cdot17}+\frac{4}{17\cdot21}\right)\)

\(=\frac{7}{4}\left(\frac{1}{1}-\frac{1}{5}+\frac{1}{5}-\frac{1}{9}+\frac{1}{9}-\frac{1}{13}+\frac{1}{13}-\frac{1}{17}+\frac{1}{17}-\frac{1}{21}\right)\)

\(=\frac{7}{4}\left(1-\frac{1}{21}\right)\)

\(=\frac{7}{4}\cdot\frac{20}{21}\)

\(=\frac{35}{21}\)

\(\frac{12}{7}:x+\frac{2}{3}=\frac{7}{5}\)

\(\frac{12}{7}:x=\frac{7}{5}-\frac{2}{3}\) 

\(\frac{12}{7}:x=\frac{11}{15}\) 

\(x=\frac{12}{7}:\frac{11}{15}\) 

\(x=\frac{12}{7}x\frac{15}{11}\) 

\(x=\frac{180}{77}\)

\(\frac{12}{7}:x+\frac{2}{3}=\frac{7}{5}\)

\(\frac{12}{7}:x=\frac{7}{5}-\frac{2}{3}\)

\(\frac{12}{7}:x=\frac{21}{15}-\frac{10}{15}\)

\(\frac{12}{7}:x=\frac{11}{15}\)

\(x=\frac{12}{7}:\frac{11}{15}\)

\(x=\frac{12}{7}\cdot\frac{15}{11}\)

\(x=\frac{180}{77}\)

Hok tốt nha bạn !!!

Dấu chấm cõ nghĩa là dấu nhân nha

36/60 ; 45/60 ; 35/60 nha bạn!

Quy đông:

\(\frac{3}{5}\)\(=\)\(\frac{3\times12}{5\times12}\)\(=\)\(\frac{36}{60}\)

\(\frac{3}{4}\)\(=\)\(\frac{3\times15}{4\times15}\)\(=\)\(\frac{45}{60}\)

\(\frac{7}{12}\)\(=\)\(\frac{7\times5}{12\times5}\)\(=\)\(\frac{35}{60}\)

# Học tốt #

7/12=11/3+1/4

7/12=1/3+1/4 (lúc nãy ghi nhầm)

1. 3/7

2. 1 - 1/2 - 1/4 - 1/8 - 1/16

=16/16 - 8/16 - 4/16 - 2/16 - 1/16

= 1/16

sorry you,offline today i k 5 times. tomorrow his appointment k offline ! thank kiu (>o<)

25/49 x 21/29 - 25/49 x 7/29 + 24/29

= 25/49 x ( 21/ 29 - 7/29 ) + 24/49

= 25/49 x 14/29 + 24/29

= 350/1421 + 24/29

= 350/1421 + 1176/1421

= 1526/1421

\(\frac{25}{49}\times\frac{21}{29}-\frac{25}{49}\times\frac{7}{29}+\frac{24}{49}\)

\(=\frac{25\times\left(21-7\right)}{49\times29}+\frac{24}{49}\)

\(\frac{50}{7\times29}+\frac{24}{49}=\frac{2450+4872}{7\times29\times49}=\frac{7322}{7\times29\times49}=\frac{1046}{1421}\)

Bằng -26/7 . Tính máy tính là ra hết ấy mà

muốn đổi hỗn số ra phân số: ta lấy số tự nhiên ở đầu nhân vs mẫu rồi cộng vs tử là xong

\(3\frac{6}{9}=\frac{3x9+6}{9}=\frac{33}{9}\)

6 nhân x = 1/2

x = 1/2 : 6 = 1/12

x : 3/7 = 7/11

x = 7/11 x 3/7 = 3/11

k mk nha

a) x = 1/2 : 6

    x= 1/12

b) x = 7/11 x 3/7

    x = 3/11