cho C= 1/101 + 1/102 + 1/103+…+ 1/200 cmr c >5/8 15/11/2021 Bởi Liliana cho C= 1/101 + 1/102 + 1/103+…+ 1/200 cmr c >5/8
Đáp án: `↓↓` Giải thích các bước giải: `C=1/101+1/102+….+1/200` `=(1/101+1/102 +….+1/120) + (1/121+1/122+….+1/150) + (1/151+1/152+….+1/180) + (1/181+1/182+….+1/200)` `C>20 . 1/120 + 30 . 1/150 + 30 . 1/180 + 20 . 1/200` `> 1/ 6 + 1/ 5 + 1/ 6 + 1/ 10` `> 19/30 = 76/120 ` `> 75/120 + 1/120` `> 5/ 8 +1/120>5/8` `=> đpcm` Bình luận
`C=1/101+1/102+…+1/200` `C=(1/101+1/102 +…+1/120)+(1/121+1/122+..+1/150)+(1/151+1/152+…+1/180)+(1/181+1/182+…+1/200)` `C>20. 1/120+30. 1/150+30. 1/180+20. 1/200` `C>1/ 6 + 1/ 5 + 1/ 6 + 1/ 10` `C>(1/ 6 +1/ 6)+(1/ 5 +1/10)` `C>1/ 3 + 3/ 10` `C>19/30=76/120` `C>75/120+1/120` `C>5/ 8 +1/120` Vậy `C>5/ 8` Bình luận
Đáp án:
`↓↓`
Giải thích các bước giải:
`C=1/101+1/102+….+1/200`
`=(1/101+1/102 +….+1/120) + (1/121+1/122+….+1/150) + (1/151+1/152+….+1/180) + (1/181+1/182+….+1/200)`
`C>20 . 1/120 + 30 . 1/150 + 30 . 1/180 + 20 . 1/200`
`> 1/ 6 + 1/ 5 + 1/ 6 + 1/ 10`
`> 19/30 = 76/120 `
`> 75/120 + 1/120`
`> 5/ 8 +1/120>5/8`
`=> đpcm`
`C=1/101+1/102+…+1/200`
`C=(1/101+1/102 +…+1/120)+(1/121+1/122+..+1/150)+(1/151+1/152+…+1/180)+(1/181+1/182+…+1/200)`
`C>20. 1/120+30. 1/150+30. 1/180+20. 1/200`
`C>1/ 6 + 1/ 5 + 1/ 6 + 1/ 10`
`C>(1/ 6 +1/ 6)+(1/ 5 +1/10)`
`C>1/ 3 + 3/ 10`
`C>19/30=76/120`
`C>75/120+1/120`
`C>5/ 8 +1/120`
Vậy `C>5/ 8`