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\(\text{Giải:}\)
\(\text{Các phân số theo thứ tự từ bé đến lớn là:}\)\(2\frac{1}{4};2;1\frac{3}{4};\frac{2}{3};\frac{2}{5}\)
\(\text{Học tốt!!}\)
a,=25/6;7/6=25/6x6/7=25/7
b,=7/2x32/6=56/3
c,=17/5-11/10=34/10-11/10=23/10
d,=8/3+11/4=32/12+33/12=65/12
\(\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{9.10}\right).100-\left[\frac{5}{2}:\left(x+\frac{266}{100}\right)\right]:\frac{1}{2}=89\)
\(\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{9}-\frac{1}{10}\right).100-\left[\frac{5}{2}:\left(x+\frac{266}{100}\right)\right]:\frac{1}{2}=89\)
\(\left(1-\frac{1}{10}\right).100-\left[\frac{5}{2}:\left(x+\frac{266}{100}\right)\right]:\frac{1}{2}=89\)
\(90-\left[\frac{5}{2}:\left(x+\frac{266}{100}\right)\right]:\frac{1}{2}=89\)
\(\left[\frac{5}{2}:\left(x+\frac{266}{100}\right)\right]:\frac{1}{2}=1\)
\(\frac{5}{2}:\left(x+\frac{266}{100}\right)=\frac{1}{2}\Rightarrow x+\frac{266}{100}=5\Rightarrow x=\frac{117}{50}\)
Vậy x = 117/50
Ta có:
\(\left(\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{9.10}\right).100\\ =\left(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{9}-\frac{1}{10}\right).100\)
\(=\left(1-\frac{1}{10}\right).100\)
\(=\frac{9}{10}.100\)
= 90
Khi đó đề bài sẽ thành : \(90-\left[\frac{5}{2}:\left(x+\frac{266}{100}\right)\right]:\frac{1}{2}=89\)
\(\Rightarrow\left[\frac{5}{2}:\left(x+\frac{266}{100}\right)\right]:\frac{1}{2}=1\)
\(\Rightarrow\frac{5}{2}:\left(x+\frac{266}{100}\right)=\frac{1}{2}\)
\(\Rightarrow x+\frac{266}{100}=5\)
\(\Rightarrow x=\frac{117}{50}\)
Vậy \(x=\frac{117}{50}\)
\(\frac{1}{1+2}+\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+\frac{1}{1+2+3+4+5}\)
\(=\frac{1}{1+2}\times\left(1+\frac{1}{1+2+3}\div\frac{1}{1+2}+\frac{1}{1+2+3+4}\div\frac{1}{1+2}+\frac{1}{1+2+3+4+5}\div\frac{1}{1+2}\right)\)
\(=\frac{1}{1+2}\times\left(1+\frac{1}{2}+\frac{3}{10}+\frac{1}{5}\right)\)
\(=\frac{1}{1+2}\times2\)
\(=\frac{2}{3}\)
ở dãy 1 thì số đứng sau bằng tổng hai số đứng trước
ta có 5 số tiếp theo la 40,74, 136,...
a) \(x+4\frac{1}{5}=5\frac{2}{3}\times10\frac{1}{2}\)
\(x+\frac{21}{5}=\frac{17}{3}\times\frac{21}{2}\)
\(x+\frac{21}{5}=\frac{119}{2}\)
\(x=\frac{119}{2}-\frac{21}{5}\)
\(x=\frac{553}{10}\)
b) \(\frac{24}{5}-x=2\frac{1}{4}:1\frac{3}{4}\)
\(\frac{24}{5}-x=\frac{9}{4}:\frac{7}{4}\)
\(\frac{24}{5}-x=\frac{9}{4}.\frac{4}{7}\)
\(\frac{24}{5}-x=\frac{9}{7}\)
\(x=\frac{24}{5}-\frac{9}{7}\)
\(x=\frac{123}{35}\)
| \(\frac{8}{9}\) | \(\frac{4}{5}\) | \(\frac{9}{8}\) | \(\frac{3}{4}\) |
| \(\frac{10}{9}\) | \(\frac{3}{4}\) | \(\frac{7}{8}\) | \(\frac{1}{6}\) |
| \(\frac{1}{4}\) | \(\frac{3}{2}\) | \(\frac{1}{5}\) | \(\frac{8}{7}\) |
| \(\frac{8}{3}\) | \(\frac{2}{15}\) | \(\frac{1}{2}\) | \(\frac{5}{4}\) |
vậy là đã dễ rồi còn lại thì bạn tự so sánh đi dễ mà
X×3 1/5-7/9= 2 1/3
X×16/5-7/9=7/3
X×16/5=7/3+7/9
X×16/5=28/9
X=28/9:16/5
X=35/36
\(1\frac{1}{5};1\frac{1}{2};1\frac{3}{5};2\frac{1}{2};2\frac{2}{3}\)