tính nhanh 1/2+2/8+3/28+4/77+5/176+6/352

0 bình luận về “tính nhanh 1/2+2/8+3/28+4/77+5/176+6/352”

1. Đáp án:

   ` 21/22`

   Giải thích các bước giải:

       `1/2+2/8+3/28+4/77+5/176+6/352`

   ` =1/1.2 + 1/2.4 + 1/4.7 + 1/7.11 + 1/11 .16 + 1/16.22`

   `= 1 – 1/12 + 1/2 – 1/4 + 1/4 – 1/7 + 1/7 – 11 + 1/11- 1/16 + 1/16 – 1/22`

   `= 1 – 1/22`

   `=22/22 – 1/22 = 21/22`

   Trả lời

2. 1/2+2/8+3/28+4/77+5/176+6/352

   =1/1.2+2/2.4+3/4.7+4/7.11+5/11.16+6/16.22

   =1/1-1/2+1/2-1/4+1/4-1/7+1/7-1/11+1/11-1/16+1/16-1/22

   =1-1/22

   =21/22

   Trả lời