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a)29 . (19 – 13) – 19 . (29 – 13)
= 29 . 6 – 19 . 16
= 174 – 304
= –130.
b)31.(-18)+31.(-81)-31
= 31. [-18 + (-81) - 1 ]
= 31. (-100)
= -3100
c)(7.3-3):(-6)
(7.3-3):(-6)
= (21-3):(-6)
= 18 : (-6)
= 3
d)72:[(-6).2+4)]
= 72 : ( -12 + 4 )
= 72 : -8
= -9
\(a,31.\left(-18\right)+31.\left(-81\right)-31\)
\(=31\left(-18-81-1\right)\)
\(=31\left(-100\right)\)
\(=-3100\)
\(b,13\left(23+22\right)-3\left(17+28\right)\)
\(=299+286-51-84\)
\(=450\)
\(\left(\frac{17}{28}+18.29+\frac{19}{30}+\frac{30}{31}\right).\left(\frac{-5}{12}+\frac{1}{4}+\frac{1}{6}\right)\)
\(=\left(\frac{17}{28}+18.29+\frac{19}{30}+\frac{30}{31}\right).\left(\frac{-5}{12}+\frac{3}{12}+\frac{2}{12}\right)\)
\(=\left(\frac{17}{28}+18.29+\frac{19}{30}+\frac{30}{31}\right).\left(\frac{-2}{12}+\frac{2}{12}\right)\)
\(=\left(\frac{17}{28}+18.29+\frac{19}{30}+\frac{30}{31}\right).0\)
\(=0\)
Bài 3 :
A = 26 + 27 + 28 + 29 + 30 + 31 + 32 + 33
=> A = ( 33 + 26 ) . 8 : 2 = 236
Vậy A = 236
\(\text{#Hok tốt!}\)
a) 2 . 31 . 12 + 4 . 6 . 42 + 8 . 27 . 3
= 24 . 31 + 24 . 42 + 24 . 27
= 24 . ( 31 + 42 + 27 )
= 24 . 100
= 2400
TÍNH HỢP LÍ
A) 31.(-18)+31.(-81)-31
=31.((-18)+(-81)-1)
=31.(-100)
=-3100
B) (-12).47+(-12).52+(-12)
=(-12).(47+52+1)
=(-12).100
=-1200
C)13.(23+22)-3.(17+28)
=13.45-3.45
=45.(13-3)
=45.10
=450
D)-48+48.(-78)+48.(-21)
=(-48).(1+78+21)
=(-48).100
=-4800
mik đầu tiên nhé bạn !
a) 2.31.12+4.6.42+8.27.3
=24.31+24.42+24.27
=24.(31+42+27)
=24.100
=2400
b) 36.28+36.82+64.69+64.41
=36.(28+82)+64.(69+41)
=36.110+64.110
=110.(36+64)
=110.100
=11000
31 . ( − 28 ) + ( − 31 ) . 12 = 31 . ( − 28 ) + 31 . ( − 12 ) = 31 . ( − 28 ) + ( − 12 ) = 31 . ( − 100 ) = − 3100.