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204-84:2=204-42=162
15.23+4.32-5.7=15.8+4.9-35=120+36-35=121
56:53+23.22=15625:125+8.4=125+32=157
164.53+47.164=164.(53+47)=164.100=16400
HỌC TỐT.
![](https://rs.olm.vn/images/avt/0.png?1311)
S = 1 + 2 + 22 + 23 + 24 + 25 + 26 + 27
= (1 + 2) + (22 + 23) + (24 + 25) + (26 + 27)
= (1 + 2) + 22(1 + 2) + 24(1 + 2) + 26(1 + 2)
= (1 + 2)(1 + 22 + 24 + 26)
= 3(1 + 22 + 24 + 26) \(⋮3\)(ĐPCM)
2S = 1 + 2 + 22 + 23 + 24 + 25 + 26 + 27
S = (1+2 ) + (22 + 23 ) + (24 + 25 ) + (26 +27)
S = 3 + 22(1+2) + 24(1+2) + 26(1+2)
S = 3+22.3 + 24.3 + 26 .3
S = 3(1+22 + 24 + 26 ) \(⋮\) 3
=> đpcm
![](https://rs.olm.vn/images/avt/0.png?1311)
a)
204 - 84:12 = 204 - 7 = 197
b)
15.23 + 4.32 - 5.7 = 15.8 + 4.9 – 5.7 = 120 + 36 - 35 = 121
c) Áp dụng:
am . an = am+n
am : an = am-n
56:53 + 23.22 = 53 + 25 = 125 + 32 = 157
d)
164.53 + 47.164 = 164(53 + 47) = 164.100 = 16400
a) 204 - 84 : 12
= 204 - 7 = 197
b) 15.23 + 4.32 - 5.7
= 15.8 + 4.9 - 35
= 120 + 36 - 35
= 156 - 35
= 121
c) 56 : 53 + 23.22
= 56 - 3 + 23 + 2
= 53 + 25
= 125 + 32
= 157
d) 164.53 + 47.164
= 164.( 53 + 47 )
= 164.100
= 16400
![](https://rs.olm.vn/images/avt/0.png?1311)
`#3107.101107`
\(A = 2 + 2^2 + 2^3 + ... + 2^{2020} + 2^{2021} + 2^{2022}\)
\(= (2 + 2^2) + (2^3 + 2^4) + ... + (2^{2021} + 2^{2022})\)
\(=2(1+2) + 2^3(1 + 2) + ... + 2^{2021}(1 + 2)\)
\(=(1 + 2)(2 + 2^3 + ... + 2^{2021})\)
\(= 3(2 + 2^3 + ... + 2^{2021})\)
Vì \(3(2 + 2^3 + ... + 2^{2021})\) \(\vdots\) \(3\)
`\Rightarrow A \vdots 3`
Vậy, `A \vdots 3.`
![](https://rs.olm.vn/images/avt/0.png?1311)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(S=\left(-2\right)^0+\left(-2\right)^1+\left(-2\right)^2+\left(-2\right)^3...+2^{2014}+2^{2015}\)
\(2S=\left(-2\right)^1+\left(-2\right)^2+\left(-2\right)^3+\left(-2\right)^4+...+\left(-2\right)^{2015}+\left(-2\right)^{^{ }2016}\)
\(2S-S=\left[\left(-2\right)^1+\left(-2\right)^2+\left(-2\right)^3+\left(-2\right)^4+...+\left(-2\right)^{2015}+\left(-2\right)^{2016}\right]\)\(-\left[\left(-2\right)^0+\left(-2\right)^1+\left(-2\right)^2+\left(-2\right)^3+...+\left(-2\right)^{2014}+\left(-2\right)^{2015}\right]\)
\(S=\left(-2\right)^{2016}-\left(-2\right)^0=\left(-2\right)^{2016}-1\)
![](https://rs.olm.vn/images/avt/0.png?1311)
a)
204-84:12
=204-7
=197
b)
15.23+4.32-5.7
=15.8+4.9-5.7
=120+36-35
=156-35
=121
c)
56:53+23.22
=56-3+23+2
=53+25
=125+32
=157
d)
164.53+47.164
=(164.(53+47)
=164.100
=16400
tìm x:
219-7(x+1)=100
=>7(x+1)=219-100
=>7(x+1)=119
=>x+1=119:7
=>x+1=17
=>x=17-1
=>x=16
(3x-6).3=34
=>(3x-6).3=81
=>3x-6=81:3
=>3x-6=27
=>3x=27+6
=>3x=33
=>x=33:3
=>x=11
a) \(204-84:12=204-7=197\)
b) \(15.2^3+4.3^2-5.7=15.8+4.9+5.7=120+36+35=156+35=191\)
c) \(5^6:5^3+2^3.2^2=5^3+2^5=125+32=157\)
d) \(164.53+47.164=164.\left(53+47\right)=164.100=16400\)
_Chúc bạn học tốt_