Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
2222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222222225444444455555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555555
a \(\frac{4}{18}+\frac{5}{13}+\frac{7}{9}+\frac{21}{13}\)
= \(\left(\frac{4}{18}+\frac{7}{9}\right)+\left(\frac{5}{13}+\frac{21}{13}\right)\)
= \(1+2\)
= \(3\)
b \(\frac{4}{3}-\frac{2}{7}-\frac{5}{7}+\frac{2}{3}\)
= \(\left(\frac{4}{3}-\frac{2}{3}\right)-\left(\frac{2}{7}+\frac{5}{7}\right)\)
= \(\frac{2}{3}-1\)
= \(-\frac{1}{3}\)
a/7/9(1/4+3/4)=7/9.1=7/9
b/13/9(16/5-14/5+3/5)=13/9.1=13/9
34cm=34/100m
524mm=524/1000m
70mm=70/1000=7/100m
a/7/9(1/4+3/4)=7/9.1=7/9
b/13/9(16/5-14/5+3/5)=13/9.1=13/9
34cm=34/100m
524mm=524/1000m
70mm=70/1000=7/100m
Đặt A = 9/4 + 9/28 +.. + 9/550
A = 9/1.4 + 9/4.7 +... + 9/22.25
A = 3( 3/1.4 + 3/4.7 + .. + 3/22.25)
A = 3 . (1/1 - 1/4 + 1/4 - 1/7 + ... +1/22 - 1/25)
A = 3 (1 - 1/25)
A = 3. 24 / 25
A = 72/25
\(3\times\left(\frac{x}{4}+\frac{x}{28}+\frac{x}{70}+\frac{x}{130}\right)=\frac{60}{13}\)
=> \(\frac{x}{4}+\frac{x}{28}+\frac{x}{70}+\frac{x}{130}=\frac{20}{13}\)
=> \(\frac{x}{1\cdot4}+\frac{x}{4\cdot7}+\frac{x}{7\cdot10}+\frac{x}{10\cdot13}=\frac{20}{13}\)
=> \(\frac{x}{3}\left(\frac{3}{1\cdot4}+\frac{3}{4\cdot7}+\frac{3}{7\cdot10}+\frac{3}{10\cdot13}\right)=\frac{20}{13}\)
=> \(\frac{x}{3}\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+...+\frac{1}{10}-\frac{1}{13}\right)=\frac{20}{13}\)
=> \(\frac{x}{3}\left(1-\frac{1}{13}\right)=\frac{20}{13}\)
=> \(\frac{x}{3}\cdot\frac{12}{13}=\frac{20}{13}\)
=> \(\frac{x}{3}=\frac{20}{13}:\frac{12}{13}=\frac{20}{13}\cdot\frac{13}{12}=\frac{5}{3}\)
=> x = 5
\(3\cdot\left(\frac{x}{4}+\frac{x}{28}+\frac{x}{70}+\frac{x}{130}\right)=\frac{60}{13}\)
\(3\cdot\left(\frac{x}{1\cdot4}+\frac{x}{4\cdot7}+\frac{x}{7\cdot10}+\frac{x}{10\cdot13}\right)=\frac{60}{13}\)
\(3\left(x-3\right)\left(\frac{3}{1\cdot4}+\frac{3}{4\cdot7}+\frac{3}{7\cdot10}+\frac{3}{10\cdot13}\right)=\frac{60}{13}\)
\(\left(3x-9\right)\left(1-\frac{1}{4}+\frac{1}{4}-\frac{1}{7}+\frac{1}{7}-\frac{1}{10}+\frac{1}{10}-\frac{1}{13}\right)=\frac{60}{13}\)
\(\left(3x-9\right)\left(1-\frac{1}{13}\right)=\frac{60}{13}\)
\(\left(3x-9\right)\cdot\frac{12}{13}=\frac{60}{13}\)
\(3x-9=\frac{\frac{60}{13}}{\frac{12}{13}}\)
\(3x-9=5\)
\(3x=5+9\)
\(3x=14\)
\(x=\frac{14}{3}\approx4,667\)
dễ mà
=5/9x7/4+13/9x7/4
=7/4x(5/9+13/9)
=7/4x18/9
=7/4x2
=7/2
nhớ chọn cho mih nha bn
\(\frac{5}{28}\times\frac{13}{9}+\frac{13}{28}\times\frac{4}{9}\)
\(=\frac{13}{28}\left(\frac{5}{9}+\frac{4}{9}\right)\)
\(=\frac{13}{28}\times1\)
\(=\frac{13}{28}\)
\(\frac{5}{28}\times\frac{13}{9}+\frac{13}{28}\times\frac{4}{9}\)
= \(\frac{65}{252}+\frac{13}{63}\)
= \(\frac{13}{28}\)