Đáp án:
Giải thích các bước giải:
Ta có :
`B = 2008/1 + 2007/2 + 2006/3 + ... + 2/2007 + 1/2008`
`B = 1 + ( 2007/2 + 1 ) + ( 2006/3 + 1 ) + ... + ( 2/2007 + 1 ) + ( 1/2008 + 1 )`
`B = 2009/2009 + 2009/2 + 2009/3 + ... + 2009/2007 + 2009/2008`
`B = 2009( 1/2 + 1/3 + ... + 1/2007 + 1/2008 + 1/2009 )`
`⇒ A/B =` `\frac{\frac{1}{2} + \frac{1}{3} + ... + \frac{1}{2007} + \frac{1}{2008} + \frac{1}{2009}}{2009(\frac{1}{2} + \frac{1}{3} + ... + \frac{1}{2007} + \frac{1}{2008} + \frac{1}{2009))`
Vậy `A/B = 1/2009`
