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Câu 1:
a) Ta có: 2n+1 là số lẻ∀n
⇒\(\left(-1\right)^{2n+1}=-1\)
Ta có: \(\left(-25\right)\cdot21\cdot\left(-2\right)^2\cdot\left(-\left|-3\right|\right)\cdot\left(-1\right)^{2n+1}\)
\(=-25\cdot21\cdot4\cdot\left(-3\right)\cdot\left(-1\right)\)
\(=75\cdot84\cdot\left(-1\right)\)
\(=-6300\)
b) Ta có: \(\left(-5\right)^3\cdot67\cdot\left(-\left|-2^3\right|\right)\cdot\left(-1\right)^{2n}\)
\(=-125\cdot67\cdot\left(-8\right)\)
\(=1000\cdot67=67000\)
c) Ta có: \(35\cdot18-5\cdot7\cdot28\)
\(=35\cdot18-35\cdot28\)
\(=35\cdot\left(18-28\right)=35\cdot\left(-10\right)=-350\)
d) Ta có: \(24\cdot\left(16-5\right)-16\cdot\left(24-5\right)\)
\(=24\cdot16-24\cdot5-24\cdot16+16\cdot5\)
\(=-24\cdot5+16\cdot5\)
\(=5\cdot\left(-24+16\right)=5\cdot\left(-8\right)=-40\)
e) Ta có: \(29\cdot\left(19-13\right)-19\cdot\left(19-13\right)\)
\(=6\cdot\left(29-19\right)=6\cdot10=60\)
g)Sửa đề: \(31\cdot\left(-18\right)+31\cdot\left(-81\right)-31\)
Ta có: \(31\cdot\left(-18\right)+31\cdot\left(-81\right)-31\)
\(=31\cdot\left(-18-81-1\right)\)
\(=31\cdot\left(-100\right)=-3100\)
h) Ta có: \(\left(-12\right)\cdot47+\left(-12\right)\cdot52+\left(-12\right)\)
\(=-12\cdot\left(47+52+1\right)\)
\(=-12\cdot100=-1200\)
k) Ta có: \(13\cdot\left(23+22\right)-3\cdot\left(17+28\right)\)
\(=13\cdot45-3\cdot45\)
\(=45\cdot\left(13-3\right)=45\cdot10=450\)
m) Ta có: \(-48+48\cdot\left(-78\right)+48\cdot\left(-21\right)\)
\(=48\cdot\left(-1-78-21\right)\)
\(=48\cdot\left(-100\right)=-4800\)
n) Ta có: \(135\cdot\left(171-123\right)-171\cdot\left(135-123\right)\)
\(=135\cdot171-135\cdot123-171\cdot135+171\cdot123\)
\(=123\cdot\left(-135+171\right)=123\cdot36=4428\)
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
\(a,31.\left(-18\right)+31.\left(-81\right)-31\)
\(=31\left(-18-81-1\right)\)
\(=31\left(-100\right)\)
\(=-3100\)
\(b,13\left(23+22\right)-3\left(17+28\right)\)
\(=299+286-51-84\)
\(=450\)
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
1) \(35.18-5.7.28=35.18-35.28=35\left(18-28\right)=-350\)
2) \(45-5\left(12+9\right)=45-60-45=-60\)
3) \(24\left(16-5\right)-16\left(24-5\right)=24.16-24.5-16.24+16.5=5\left(16-24\right)=5.8=40\)
4) \(29\left(19-13\right)-19\left(29-13\right)=29.19-29.13-19.29+19.13=13\left(19-29\right)=-130\)
5) \(31.\left(-18\right)+31.\left(-81\right)-31=-31.\left(18+81+1\right)=-3100\)
6) \(\left(-12\right).47+\left(-12\right).52+\left(-12\right)=\left(-12\right)\left(47+52+1\right)=-1200\)
7) \(13\left(23+22\right)-3\left(17+28\right)=13.45-3.45=45.\left(13-3\right)=450\)
8) \(-48+48.\left(-78\right)+48.\left(-21\right)=-48\left(1+78+21\right)=-4800\)
Máy tính đâu,nó sinh ra là để làm gì???
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