Dạng 1:
Bài 1:
a) (-47)+(-53)= -100
b) (-15)+(-40)= -55
b) 52-72= -20
c) (-25).(-125)=3125
d) (-225):25= -9
e) (-2-4).(-2+6)= -6+4= -2
Bài 2:
a) 54.(-78+28)
= 54.(-50)
= -2700
b) 6.(-65+25)
= 6.(-40)
= -240
c) (-23+47).(-2)
= 24.(-2)
= -48
Bài 3:
a) 35.18-5.7.28
= (35-5).(28-18).7
= 30.10.7
= 2100
b) 24.(16-5)-16.(24-5)
= 24.16-5-16.24-5
= (24-24).(16-16).(5-5)
= 0.0.0
= 0
c) 29.(19-13)-19.(29-13)
= 29.19-13-19.29-13
= (29-29).(19-19).(13-13)
= 0.0.0
= 0
d) (-12).47+(-12).52+(-12)
= (-12).(47+52)
= (-12).99
= -1188
Dạng 2:
a) (-4).(-3).25.(-8)
= [(-4).25].[(-3).(-8)]
= (-100).(-24)
= 2400
b) 7.(-25).(-3)².(-4)
=7.(-25).9.(-4)
=(7.9).[(-25).(-4)]
= 63.100
= 6300
d) [93-(20-7)]:16
= [93-13]:16
= 80:16
= 5
e) 53-(-51)+(-53)+49
= 53+51+(-53)+49
= [53+(-53)]+(51+49)
= 0+100
= 100
f) 168-(49)+(-68)+4
=[168+(-68)]-(49-4)
=100-45
=55
h) 25.(-124)+124.25
= (25.25)+[(-124)+124]
= 625+0
= 625
g) 53-(-7)+(-53)-49
= 53+7+(-53)-49
= [53+(-53)]+(49-7)
= 0+42
= 42
i) (-11).36-64.11
=11.(-36)-64.11
= 11.(-36-64)
= 11.(-100)
= -1100
k) 125.(-24)+24.125
= (125.125).[(-24)+24]
= 15625.0
= 0
l) 125.(-23)+23.225
= (125.225).[(-23)+23]
= 2750.0
= 0
m) (-11).36+64.(-11)
= [(-11).(-11)].(36+64)
= 121.100
= 12100
Dạng 3:
a) 5+x= 9-10
5+x= -1
x= 5+(-1)
x= 4
b) x-3= 7
x= 7+3
x= 10
c) |x-2|=8
TH1: x-2= 8 TH2: x-2= -8
x= 8+2 x= -8+2
x= 10 x= -6
Vậy x∈{ 10; -6}
Phần sau mk ko bt lm, xl bn nha
Chúc bn hk tốt!!!
