Đáp án+Giải thích các bước giải:
`A=3/4 . 8/9 . 15/16 . .... 9999/10000`
`=(1.3)/(2.2) . (2.4)/(3.3) ..... (99.101)/(100.100)`
`=[(1.2.3.....99).(3.4.....101)]/[(2.3.....100)(2.3...100)]`
`=101/(100*2)`
`=101/200`
`B=8/9 . 15/16 . 24/25 .....3599/3600`
`=(2.4)/(3.3) . (3.5)/(4.4) . (4.6)/(5.5) . ....(59.61)/(60.60)`
`=[(2.3.4....59)(4.5.6....91)]/[(3.4.5....60)(3.4.5...60)]`
`=(2*61)/(60*3)`
`=61/(30.3)`
`=61/90`
