5^2/1.6 + 5^2/6.11 +…..+ 5^2/26.31(tính nhanh) x + 3/10 = 4/5 2/9 – 3.x = -4/3 (3/5 – x ) + 13/20 = 5/6 (2x – 1/2) =3/4

0 bình luận về “5^2/1.6 + 5^2/6.11 +…..+ 5^2/26.31(tính nhanh) x + 3/10 = 4/5 2/9 – 3.x = -4/3 (3/5 – x ) + 13/20 = 5/6 (2x – 1/2) =3/4”

1. 1. `5^(2)/1.6+5^(2)/6.11+…+5^(2)/26.31`

   `=5.[(1-1/6)+(1/6-1/11)+…+(1/21-1/26)+(1/26-1/31)]`

   `=5.(1-1/31)`

   `=5.30/31`

   `=150/31`

   2. `x+3/10=4/5`

   `<=>x=4/5-3/10`

   `<=>x=1/2`

   Vậy `x=1/2`

   3. `2/9-3.x=-4/3`

   `<=>-3.x=-4/3-2/9`

   `<=>-3.x=-14/9`

   `<=>-3x=14/27`

   Vậy `14/27`

   4. `(3/5-x)+13/20=5/6`

   `<=>3/5-x=11/60`

   `<=>x=11/60-3/5`

   `<=>-5/12`

   Vậy `-5/12`

   5. `2x-1/2=3/4`

   `<=>2x=5/4`

   `<=>x=5/8`

   Vậy `x=5/8`

   `#Study well`

   Trả lời

2. Đáp án:

    

   Giải thích các bước giải:

    `a) 5. (5/(1. 6)+ 5/(6. 11)+…+ 5/(26. 31))`

   `= 5. (1- 1/6+ 1/6- 1/11+…+ 5/26- 5/31)`

   `= 5. (1- 1/31)`

   `= 5. 30/31`

   `= 150/31`

   `b) x+ 3/10= 4/5`

   `x= 4/5- 3/10`

   `x= 8/10- 3/10`

   `x= 5/10`

   `x= 1/2`

   `c) 2/9- 3. x= -4/3`

   `3. x= 2/9- (-4/3)`

   `3. x= 2/9- (-12/9)`

   `3. x= 14/9`

   `x= 14/9: 3`

   `x= 14/9. 1/3`

   `x= 14/27`

   `(3/5- x)+ 13/20= 5/6`

   `(3/5- x)= 5/6- 13/20`

   `(3/5- x)= 50/60- 39/60`

   `(3/5- x)= 11/60`

   `x= 3/5- 11/60`

   `x= 36/60- 11/60`

   `x= 25/60`

   `x= 5/12`

   `2x- 1/2= 3/4`

   `2x= 3/4+ 1/2`

   `2x= 3/4+ 2/4`

   `2x= 5/4`

   `x= 5/4: 2`

   `x= 5/4. 1/2`

   `x= 5/8`

   Trả lời