Giúpppppppppppppppppppp

Ta có :

`M=1/{1.5}+2/{5.13}+3/{13.25}+4/{25.41}`

`M = 1/4 . 4/{1.5}+ 2/8 . 8/{5.13}+3/12 . 12/{13.25} + 4/16 . 16/{25.41}`

`M = 1/4 . 4/{1.5}+ 1/4 . 8/{5.13}+1/4 . 12/{13.25} + 1/4 . 16/{25.41}`

`M =1/4 (4/{1.5}+8/{5.13}+12/{13.25}+16/{25.41})`

`M = 1/4(1-1/5+1/5-1/13+1/13-1/25+1/25-1/41)`

`M=1/4(1-1/41)`

`M=1/4 . 40/41`

`M=40/164=10/41`

`N=2/{1.7}+3/{7.16}+4/{16.28}+5/{28.43}+6/{43.61}`

`N=2/6 . 6/{1.7}+3/9 . 9/{7.16}+4/12 . 12/{16.28} + 5/15 . 15/{28.43} + 6/18 . 18/{43.61}`

`N=1/3 . 6/{1.7}+1/3 . 9/{7.16}+1/3 . 12/{16.28} + 1/3 . 15/{28.43} + 1/3. 18/{43.61}`

`N=1/3(6/{1.7}+9/{7.16}+12/{16.28}+15/{28.43}+18/{43.61})`

`N=1/3(1-1/7+1/7-1/16+1/16-1/28+1/28-1/43+1/43-1/61)`

`N=1/3(1-1/61)`

`N=1/3 . 60/61`

`N=60/183=20/61`

Vì `10/41=610/2501<20/61=820/2501`

`=> M<N`

`-` Vậy : `M<N`

`#BaoNgoc`