Chứng Minh rằng: 91/1.4+91/4.7+91/7.10+…….+91/88.91=30

Question

Chứng Minh rằng:
91/1.4+91/4.7+91/7.10+…….+91/88.91=30

in progress 0
Mackenzie 20 phút 2021-09-26T18:39:30+00:00 2 Answers 0 views 0

Answers ( )

    0
    2021-09-26T18:40:44+00:00

    9/1.4+9/4.7+9/7.10+…+9/88.91=30

    =91/3. (3/1.4+3/4.7+3/7.10+…+3/88.91)

    =91/3. (1-1/4+1/4-1/7+1/7-1/10+…+1/88-1/91)

    =91/3*90/91=30

     

    0
    2021-09-26T18:41:28+00:00

    Đáp án:30=30

     

    Giải thích các bước giải.=>91/3.(3/4.7+3/7.10+….+3/88.91)=30

     =>91/3.(1- 1/4+1/4-

    1/7+1/7-1/10+…+18/88-1/91)=30

    =>91/3.(1-1/91)=30

    =>91/3.90/91=30

    30=30

    Vậy  

    =>91/4.7+91/7.10+…+91/88.91=30

Leave an answer

Browse

35:5x4+1-9:3 = ? ( )