Bài 1:
a,(-370)+ 114 +236+370
= 114 +236
= 350
b, (-120) + (-130) + 360 + (-110)
=(-120-110) + (-130+360)
=- 230 + 230
= 0
c, 25 + 37- 48 -25 - 37
= (25 -25) + (37-37 ) -48
= -48
d, (-125) - (19 -125)
= (-125) -19 +125
= -19
e, 100 - [25 - (-19 -11)]
= 100 -25 - 19 -11
=75 -30
= 45
f, 271 - [ (-43)+ 271 -(-17)]
= 271 + 43 - 271 - 17
= 26
g,35.(-29) + (-29).65
= (-29). (35 +65)
=(-29).100
= -2900
h, 22.(-8).(-25).(125).18
=22.200.2250
=4400 .2250=9900000
i, 48: (-6.4 +8)
= 48: (-24 +8)
= 48 : (-16)=-3
j, -3.7 -4.(-5) +1
=-21 + 20 +1
= 0
k, 16 + (102 -7,6)-(94.17 -27.94)
= 16 +94,4 -( 1598 - 2538)
=16 + 94,4 -1598 +2538
=110,4 +940 =1050,4
l, -2019.2020 +1010.38
= - 4078380 +38380
=-4040000
m, 1 - 2 - 3 -4 +5 - 6 -7 - 8 +9 -10 -11 -12 +....+ 97 -98 -99 -100
= (1- 2-3 -4 ) + (5 -6 -7 -8)+ (9-10-11-12)+....(97 -98-99-100)
= (-8) + (-16)+ (-24)+...(-200)
= (-8) .(1+2+3+...+25)
=(-8) .[(25-1) : 1 +1 .26:2)]
=(-8).325=-2600
Bài 2
a) -20 +35 -x = -20
=> 35 - x =-20 + 20
=>35 - x = 0
=> x =35
b) 3x +17 =12
=> 3x = -5
=> x = -5/3