So sanhs hai phaan soos 2022 202
2021 201
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a) Ta có:
2A=2.(12+122+123+...+122020+122021)2�=2.12+122+123+...+122 020+122 021
2A=1+12+122+123+...+122019+1220202�=1+12+122+123+...+122 019+122 020
Suy ra: 2A−A=(1+12+122+123+...+122019+122020)2�−�=1+12+122+123+...+122 019+122 020
−(12+122+123+...+122020+122021)−12+122+123+...+122 020+122 021
Do đó A=1−122021<1�=1−122021<1.
Lại có B=13+14+15+1360=20+15+12+1360=6060=1�=13+14+15+1360=20+15+12+1360=6060=1.
Vậy A < B.
`#3107.101107`
`a,`
`45 - (29 + 45)`
`= 45 - 29 - 45`
`= -29`
`b,`
`202 - (202 + 148)`
`= 202 - 202 - 148`
`= -148`
`c,`
`(209 - 140) - 97 - 140 - 209`
`= 209 - 140 - 97 - 140 - 209`
`= (209 - 209) - (140 +140) - 97`
`= -280 - 97`
`= -377`
`d,`
`(2021-2022)-(2023-2022)`
`= 2021 - 2022 - 2023 + 2022`
`= 2021 - 2023 - (2022 - 2022)`
`= 2 - 0 = 2`
\(\frac{201}{202}+\frac{202}{205}\)Và \(201+\frac{202}{202}+205\)
\(=\frac{201}{202}=\frac{201}{202}+\frac{1}{202}=\frac{202}{202}\)
\(\frac{202}{205}=\frac{202}{205}+\frac{3}{205}=\frac{205}{205}\)
\(201+1+205\)
Vậy \(1+1=2\)và \(407\)
=> \(\frac{201}{202}+\frac{202}{205}< 201+\frac{202}{202}+205\)
Ta có: \(\frac{201+202}{202+205}=\frac{201}{202+205}+\frac{202}{202+205}\)
Ta có: 202<202+205 => \(\frac{201}{202}>\frac{201}{202+205}\)(1)
205<202+205 => \(\frac{202}{205}>\frac{202}{202+205}\)(2)
Từ (1) và (2) => \(\frac{201}{202}+\frac{202}{205}>\frac{201+202}{202+205}\)
ta có: \(\frac{2008}{2008\cdot2009}=\frac{2008}{2008}\cdot\frac{1}{2009}=1\cdot\frac{1}{2009}\)
\(\frac{2009}{2009\cdot2010}=\frac{2009}{2009}\cdot\frac{1}{2010}=1\cdot\frac{1}{2010}\)
Vì 2009<2010 nên \(\frac{1}{2009}>\frac{1}{2010}nên\frac{2008}{2008\cdot2009}>\frac{2009}{2009\cdot2010}\)
Chúc bạn học tốt!^_^
\(\frac{200+201}{201+202}=\frac{200}{201+202}+\frac{201}{201+201}\)
Mà \(201<201+202\Rightarrow\frac{200}{201}>\frac{200}{201+202}\)
\(\frac{201}{202}>\frac{201}{201+202}\)
=> \(\frac{200}{201}+\frac{201}{202}>\frac{200+201}{201+202}\)
\(\frac{200}{201}+\frac{201}{202}=1,99...>1>\frac{401}{403}=\frac{200+201}{201+202}\)