Bài 1 : Tính nhanh
a, 248 + ( -12 ) + 2064 + ( -236 )
b, ( -298 ) + ( -300 ) + ( -302 )
c, 5 + ( -7 ) + 9 + ( -11 ) + 13 + ( -15 )
d, ( -6 ) + 8 + ( -10 ) + 12 + ( -14 ) + 16
e, 456 + [58 + ( - 456 ) + ( -38 ) ]
Bài 2 : Bỏ dấu ngoặc rồi tính
a, 8 - ( 3 + 7 )
b, ( -5 ) - ( 9 - 12 )
c, ( 5674 - 97 ) + ( 97 + 18 - 5674 )
d, ( 13 - 135 + 49 ) - ( 13 + 49 )
e, x + 8 - ( x + 22 )
f, - ( x + 5 ) + ( x + 10 ) - 5
Bài 1:
a) 248 + (-12) + 2064 + (-236)
= 248 - 236 + 2064 - 12
= 12 + 2052
= 2064
b) (-298) + (-300) + (-302)
= -298 - 302 - 300
= -600 - 300
= -900
c) 5 + (-7) + 9 + (-11) + 13 + (-15)
= -2 - 2 - 2
= -6
d) (-6) + 8 + (-10) + 12 + (-14) + 16
= 2 + 2 + 2
= 6
e) 456 + [58 + (-456) + (-38)]
= 456 - 456 + 58 - 38
= 0 + 20
= 20
Bài 2:
a) 8 - (3 + 7)
= 8 - 3 - 7
= -2
b) (-5) - (9 - 12)
= -5 - 9 + 12
= -2
c) (5674 - 97) + (97 + 18 - 5674)
= 5674 - 97 + 97 + 18 - 5674
= 18
d) (13 - 135 + 49) - (13 + 49)
= 13 - 13 - 135 + 49 - 49
= -135
e) x + 8 - (x + 22)
= x + 8 - x - 22
= -14
f) - (x + 5) + (x + 10) - 5
= -x - 5 + x + 10 - 5
= 0