Đáp án+Giải thích các bước giải:

`a;  ( x - 1)/10 + (x - 1)/10+(x-1)/12=(x-1)/20+(x-1)/100`

`=>(x-1)(1/10+1/10+1/12-1/20-1/100) = 0`

`Do  1/10 + 1/10 + 1/12 - 1/20 - 1/100  \ne  0`

`=> x - 1 = 0`

`=> x = 1`

`Vậy  x = 1`

`b; ( x - 1 )/65 + ( x - 3 )/63 = ( x - 5 )/61 + (x - 7 )/59`

`=> ( x - 1 )/65 - 1 + ( x - 3 )/63 - 1 = ( x - 5 )/61 - 1 + ( x - 7 )/59 - 1`

`=> ( x - 66 )/65 + ( x - 66 )/63 = ( x - 66 )/61 + ( x - 66 )/59`

`=> ( x - 66 )( 1/65 + 1/63 - 1/61 - 1/59 ) = 0`

`Do  1/65 + 1/63 - 1/61 - 1/59  \ne  0`

`=> x - 66 = 0`

`=> x = 66`

`Vậy  x = 66`

`c; ( x - 100 )/24 + ( x - 98 )/26 + ( x - 96 )/28 = 3`

`=> ( x - 100 )/24 - 1 + ( x - 98 )/26 - 1 + ( x - 96 )/28 - 1 = 0`

`=> ( x - 124 )/24 + ( x - 124 )/26 + ( x - 124 )/28 = 0`

`=> ( x - 124 )( 1/24 + 1/26 + 1/28 ) = 0`

`Do  1/24 + 1/26 + 1/28  \ne  0`

`=> x - 124 = 0`

`=> x = 124`

`Vậy  x = 124`