Tính hợp lý:
a,457+(123-457)-4
b,2019(513+1759)-(-513)
c,35-107+207-35+(-207)
d,307+(-17)-307+77
e,-(-2019)+(-2019)-4001+102
f,|-85|-(-15).3
g,101.107+101.18-25.101
h,15-(-85)+513-(-500+513)
k,(-118)+(-31)+98+|-118|+(-69)
l,117.(15-116)+116.(117-20)
m,125.(-176)+125.76+100.125
n,719.89-719.(-11)-100.719
o,1513.177-1513.77+100.(-77)
p,-69.|-415|-31.|415|
q,(-219).(85-417)-85.(417-219)
r,(-167).(617-34)-617.(34-167)
Tính hợp lý: a,457+(123-457)-4 b,2019(513+1759)-(-513) c,35-107+207-35+(-207) d,307+(-17)-307+77 e,-(-2019)+(-2019)-4001+102 f,|-85|-(-15).3 g,101.107
By Lydia
a,457+(123-457)-4
=457+123-457-4
=(457-457)+(123-4)
=0+119=119
c,35-107+207-35+(-207)
=35-107+207-35-207
=(35-35)+(207-207)-107
=0+0-107=-107
d,307+(-17)-307+77
=307-17-307+77
=(307-307)+(77-17)
=0+60=60
e,-(-2019)+(-2019)-4001+102
=2019-2019-4001+102
=0-3899=-3899
f,|-85|-(-15).3
=85+15.3
=85+45=130
g,101.107+101.18-25.101
=101.(107+18-25)
=101.100=10100
h,15-(-85)+513-(-500+513)
=15+85+513+500-513
=(513-513)+(15+85)+500
=0+100+500=600
k,(-118)+(-31)+98+|-118|+(-69)
=-118-31+98+118-69
=(-118+118)-(31+69)+98
=0+100+98=198
m,125.(-176)+125.76+100.125
=125.(-176+76+100)
=125.0=0
n,719.89-719.(-11)-100.719
=719.(89+11-100)
=719.0=0
p,-69.|-415|-31.|415|
=-69.415-31.415
=415.(-69-31)
=415.(-100)=-41500