a)
3 ( 2 x - 5 ) = - 21
6 x - 15 = - 21
6 x = - 21 + 15
6 x = - 6
x = ( - 6 ) : 6
x = - 1
b)
- 5 ( 3 x + 4 ) = - 35
- 15 x - 20 = - 35
- 15 x = - 35 + 20
- 15 x = - 15
x = ( - 15 ) : ( - 15 )
x = 1
c)
- 3 ( 2 x + 7 ) - 5 = - 50
- 6 x - 21 - 5 = - 50
- 6 x = - 50 + 26
- 6 x = - 24
x = (- 24 ) : ( - 6)
x = 4
d)
( x - 2 ) : 3 = - 1
x - 2 = ( - 1) · 3
x - 2 = - 3
x = - 3 + 2
x = - 1
e)
( x + 1 ) : 2 - 7 = - 10
( x + 1 ) : 2 = - 10 + 7
x + 1 = - 3 × 2
x + 1 = - 6
x = - 6 - 1
x = - 7
f)
2 × [ - 3 ( x - 2 ) - 1 ] + 5 = - 45
2 × [ - 3 ( x - 2 ) - 1] = - 45 - 5
2 × [ - 3 ( x - 2 ) - 1] = - 50
- 3 ( x - 2 ) - 1 = - 50 : 2
- 3 ( x - 2 ) - 1 = - 25
- 3 ( x - 2 ) = - 25 + 1
- 3 ( x - 2 ) = - 24
x - 2 = ( - 24 ) : ( - 3)
x - 2 = 8
x = 8 + 2
x = 10
sau:
2 × [ - 3 ( x - 2 ) - 1 ] + 5 = - 45
2 × ( - 3 x + 6 - 1 ) + 5 = - 45
- 6 x + 10 + 5 = - 45
- 6 x + 15 = - 45
- 6 x = - 45 - 15
- 6 x = - 60
x = ( - 60 ) : ( - 6)
x = 10
