Đáp án:
B1:
a)2915
b)-21
c)-44
d)-253
e)82
f)-45
g)10
h)-10
i)20
k)9
m)-59
n)19
o)-1
p)-25
q)-125
r)30
s)-3
B2:
a)5800
b)2619
c)12800
d)2442
e)3500
g)3481
h)5200
i)4000
B3:
a)x=2
b)x=31
c)x=10
d)x=21
Giải thích các bước giải:
B1:
a)2763+152=2915
b)-7+(-14)=-21
c)-35+(-9)=-44
d)-5+(-248)=-253
e)-23+105=82
f)78+(-123)=-45
g)23+(-13)=10
i)26+(-6)=20
k)19+(23-33)=19+(-10)=9
m)(-12-44)+(-3)=-56-3=-59
n)4-(-15)=19
o)99-[109+(-9)]=99-100=-1
p)-75+50=-25
q)-75+(-50)=-125
r)-23+13+(-17)+57=-10+40=30
B2:
a)58.75+58.50-58.25
=58(75+50-25)
=58.100
=5800
b)27.39+27.60-2.27
=27(39+60-2)
=27.97
=2619
c)128.46+128.32+128.22
=128(46+32+22)
=128.100
=12800
d)66.25-5.66+66.14+3.66
=66(25-5+14+3)
=66.37
=2442
e)12.35+35.182-35.94
=35(12+182-94)
=35.100
=3500
g)27.121-84.27+73.34
=27(121-84)+73.34
=27.37+73.34
=999+2482
=3481
h)125.98-125.46-52.25
=125(98-46)-52.25
=125.52-52.25
=52(125-25)
=52.100
=5200
i)136.23+136.17-40.36
=136(23+17)-40.36
=136.40-40.36
=40(136-36)
=40.100
=4000
B3:
a)x-7=-5
⇔x=-5+7
⇔x=2
b)128-3.(x+4)=23
⇔128-3x-12=23
⇔-3x=23-128+12
⇔-3x=-93
⇔x=31
c)[(6x-39):7].4=12
⇔(6x/7-39/7).4=12
⇔24x/7-156/7=12
⇔24x-156=84
⇔24x=84+156
⇔24x=240
⇔x=10
d)(x:3-4).5=15
⇔5x/3-20=15
⇔5x-60=45
⇔5x=45+60
⇔5x=105
⇔x=21
Học tốt!!!
