Đáp án + Giải thích các bước giải:
a, `-5/6 - x = 7/12 + (-1)/3`
` -5/6 - x = 7/12 - 4/12`
` -5/6 - x = 1/4`
` x = -5/6 - 1/4`
` x = -10/12 - 3/12`
` x = -13/12`
Vậy `x = -13/12`
b, `1/2x - 3/4 = 14/9 . 3/7`
` 1/2x - 3/4 = 2/3`
` 1/2x = 2/3 + 3/4`
` 1/2x = 8/12 + 9/12`
` 1/2x = 17/12`
` x = 17/12 . 2`
` x = 17/6`
Vậy `x = 17/6`
c, `(x - 1/2) . 1/3 + 5/7 = 9 5/7`
` (x - 1/2) . 1/3 = 9 5/7 - 5/7`
` (x - 1/2) . 1/3 = 9`
` x - 1/2 = 9 . 3`
` x - 1/2 = 27`
` x = 27 + 1/2`
` x = 54/2 + 1/2`
` x = 55/2`
Vậy `x = 55/2`
d, `x + 3/(-15) = 1/3`
` x - 1/5 = 1/3`
` x = 1/3 + 1/5`
` x = 8/15`
Vậy `x = 8/15`
m, `x + 30% x = -1,31`
` x(1 + 3/10) = -131/10`
` x . 13/10 = -131/10`
` x = -131/10 : 13/10`
` x = -131/13`
Vậy `x = -131/13`
n, `(8,5 - x^2) . (-1 4/7) = 11/14`
` (17/2 - x^2) . (-11)/7 = 11/14`
` 17/2 - x^2 = 11/14 : (-11)/7`
` 17/2 - x^2 = 1/2`
` x^2 = 17/2 - 1/2`
` x^2 = 4`
` x = \pm 2`
Vậy `x \in {-2 ; 2}`