Đáp án`+`Giải thích các bước giải:

 `1, 3(5x - 1) - x(x - 2) +x^2 - 13x = 7`

`<=> 15x - 3 - x^2 + 2x +x^2 -1 3x =7`

`<=> 4x = 10`

`<=> x=  5/2`

Vậy `x = 5/2`

`3, 2(5x -8) - 3(4x - 5) = 4(3x-  4) + 11`

`<=> 10x - 16 - 12x + 15 = 12x - 16 + 11`

`<=> -2x -1 = 12x -5`

`<=> 12x + 2x = -1 + 5`

`<=>14x = 4`

`<=> x = 2/7`

Vậy `x=  2/7`

`5, 5(3x + 5) - 4(2x - 3) = 5x + 3(2x + 12)`

`<=> 15x + 25 - 8x + 12 = 5x + 6x + 36`

`<=> 7x + 37 = 11x + 36`

`<=> -4x = -1`

`<=> x=  1/4`

Vậy `x = 1/4`

`***`sharksosad