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A = 100 - [ 60 - ( 9 - 2 )2 ] . 33 . 70
A = 100 - [ 60 - 72 ] . 27 . 1
A = 100 - [ 60 - 49 ] . 27
A = 100 - 11 . 27
A = 100 - 297
A = -197
A= 100-[60-(9-2)2].33.70
A=100-[60-(7)2].27.1
A=100-[60-49].27
A=100-11.27
A=100-297
A=-197
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\(\Leftrightarrow100-\left(60-7^2\right)\times9\)\(\Leftrightarrow100-11\times9\)
\(\Leftrightarrow100-99=1\)
100 - [ 60 - ( 9 - 2 )2] . 32
= 100 - ( 60 - 72) . 9
= 100 - ( 60 - 49 ) . 9
= 100 - 11 . 9
= 100 - 99
= 1
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a) 2.A = 2 + 22 + 23 + ...+ 261
=> 2.A - A = (2 + 22 + 23 + ...+ 261) - (1 + 2 + ...+ 260) = 261 - 1 => A = 261 - 1
b) 32.B = 33 + 35 + 37 + ...+ 383
=> 32.B - B = ( 33 + 35 + 37 + ...+ 383 ) - (3 + 33 + 35 + 37 + ...+ 381) = 383 - 3 => 8B = 383 - 3 => B = (383 - 3)/8
c) 23.C = 26 + 29 + ...+ 293
=> 23.C - C = 293 - 23 => 7.C = 293 - 23 => C = (293 - 23)/7
d) 3.D = 3101 - 3100 + 399 - ....- 32
=> 3.D + D = 3101 - 3 => D= (3101 - 3) /4
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a) {[( 32 + 1 ) . 10 - ( 8 : 2 + 6 ) ] : 2 } + 55 -( 10 : 5 )3
= ( 10 . 10 - 10 : 2 ) + 55 - 6
= 90 : 2 ) + 55 - 6
= 45 + 55 - 6
= 100 - 6
= 94
b) 100 - [ 60 - ( 9 - 2 )2 ] . 32
= 100 - [ 60 - 72 ] . 9
= 100 - [ 60 - 49 ] . 9
= 100 - 11 . 9
= 100 - 99
= 1
c) [ ( 1253 ) . 75 - ( 175 )5 : 5 ] : 20162017
= 0 : 20162017
= 0
+ bài d kg hiểu! Xin lỗi
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Ta có: A= 3 + 32 +33 + 34 + ...+ 3100
=> 3A = 32 +33 + 34 + ...+ 3101
=> 3A - A = 3101 - 3
=> 2A = 3101 - 3
=> A = 3101 - 3 / 2
Chứng minh
A = 2 + 22 + 23 + 24 + ...+ 260 chia hết cho 31
A = (2 + 22 + 23 + 24 + 25) + ..... + (256 + 257 + 258 + 259 + 260)
= 2.( 1 + 2 + 4 + 8 + 16) + ..... + 256.(1 + 2 + 4 + 8 + 16)
= 2.31 + .... + 256.31
= 31.(2 + .... + 256) chia hết cho 3`1
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a)Đặt A=2+22+...+2100
2A=2(2+22+...+2100)
2A=22+23+...+2101
2A-A=(22+23+...+2101)-(2+22+...+2100)
A=2101-2
b)Đặt B=5+52+...+560
5B=5(5+52+...+560)
5B=52+53+...+561
5B-B=(52+53+...+561)-(5+52+...+560)
4B=561-5
\(B=\frac{5^{61}-5}{4}\)
- Đặt A = 2 + 22 + 23 + ... + 2100
2A = 22 + 23 + 24 + ... + 2101
2A - A = (22 + 23 + 24 + ... + 2101) - (2 + 22 + 23 + ... + 2100)
A = 2101 - 2
- Đặt B = 5 + 52 + 53 + ... + 560
5B = 52 + 53 + 54 + ... + 561
5B - B = (52 + 53 + 54 + ... + 561) - (5 + 52 + 53 + ... + 560)
4B = 561 - 5
\(B=\frac{5^{61}-5}{4}\)
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sau 58 ,7,50 ,2,-60 là phép tính khác .
mấy b giúp mk nha ?