Help me please làm giúp tui để tui còn đi ngủ nhé

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Bài `5:`

Ta có:

`A=200/1+199/2+198/3+...+1/200+200`

`A=(200/1+1)+(199/2+1)+(198/3+1)+...+(1/200+1)`

`A=(200+1)/1+(199+2)/2+(198+3)/3+...+(1+200)/200`

`A=201/1+201/2+201/3+..+201/200`

`A= 201 . (1+1/2 +1/3+...+1/200)`

Ta có:

`B=1+1/2 +1/3+...+1/200`

`A:B=(201.B)/B=201`

Vậy `A:B=201`

$\color{#29B6F6}{\heartsuit Phuongg \ Li nhh \heartsuit}$