Câu 8:
a) (17 - 229) + (17 -25 + 229)
= 17 - 229 + 17 -25 + 229
= (17 + 17) + (-229 + 229) - 25
= 34 + (-25)
= 9
b) ( 125 – 679 + 145) – ( 125 – 679 )
= 125 – 679 + 145 – 125 + 679
= (125 - 125) + (679 - 679) + 145
= 145
Câu 9:
a) 15 – ( 4 – x) = 6
15 - 4 + x = 6
11 + x = 6
x = 6 - 11
x = -5
b) - 30 + ( 25 – x) = - 1
- 30 + 25 – x = - 1
- 5 - x = -1
x = -5 - (-1)
x = -4
c) x – ( 12 – 25) = -8
x – 12 + 25 = -8
x + 13 = -8
x = -8 - 13
x = -21
d) ( x – 29 ) – ( 17 – 38 ) = - 9
x – 29 – 17 + 38 = - 9
x - 8 = -9
x = -9 + (-8)
x = -17
Câu 10:
a) x – 5 = - 1
x = - 1 + 5
x = 4
b) x + 30 = - 4
x = -4 - 30
x = -34
c) x – ( - 24) = 3
x - 24 = 3
x = 3 + 24
x = 27
d) 22 – ( - x ) = 12
22 + x = 12
x = 12 - 22
x = -10
Câu e,f mình không bik làm
Thông cảm