Q= 11/12+19/20+29/30+41/42+55/56+71/72+89/90+109/110

0 bình luận về “Q= 11/12+19/20+29/30+41/42+55/56+71/72+89/90+109/110”

1. Đáp án:

    `Q= 256/33`

   Giải thích các bước giải:

    `Q= 11/12 + 19/20 + 29/30 + 41/42 + 55/56 + 71/72 + 89/90 + 109/110`

   `Q= ( 1- 1/12 )+( 1-1/20) + (1- 1/30) + (1- 1/42) + (1-1/72) +(1-1/90) + (1- 1/110)`

   `Q= 8 – ( 1/12 + 1/20 + 1/30 + 1/42 + 1/72 + 1/90 + 1/110)`

   `Q= 8- ( 1/(3xx4)+ 1/(4xx5)  + 1/(5xx6)  + 1/(6xx7) + 1/(7xx8) + 1/(8xx9) + 1/(9xx10) + 1/(10xx11))`

   `Q= 8 – ( 1/3 – 1/4 + 1/4- 1/5+…+ 1/10 – 1/11)`

   `Q= 8 – ( 1/3 – 1/11)`

   `Q= 8- 8/33`

   `Q = 256/33`

   Vậy `Q= 256/33`

   Trả lời

2. Đáp án: + Giải thích các bước giải:

   `Q = 11/12 + 19/20 + 29/30 + 41/42 + 55/56 + 71/72 + 89/90 + 109/110`

   `= 1 – 1/12  + 1 – 1/20  + 1 – 1/30 + 1 – 1/42 + 1 – 1/56 + 1 – 1/72 + 1 – 1/90 + 1 – 1/110`

   `= (1 + 1 + 1 + … + 1 + 1) – ( 1/12 + 1/20 + 1/30 + 1/42 + 1/56 + 1/72 + 1/90 + 1/110 )`

   `= 8 – ( 1/3.4 + 1/4.5 + 1/5.6 + 1/6.7 + 1/7.8 + 1/8.9 + 1/9.10 + 1/10.11 )`

   `= 8 – (1/3 – 1/4 + 1/4 – 1/5 + 1/5 – 1/6 + 1/6 + 1/7 – 1/8 + 1/8 – 1/9 + 1/9 – 1/10 + 1/10 – 1/11 )`

   `= 8 – (1/3 – 1/11)`

   `= 8 – 8/33`

   `= 264/33 – 8/33`

   `= 256/33`

   Trả lời