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Câu 1:
a) A = {1;2;3;4;5}
B= { 4;5}
b) C1: A giao B = B
C2: A giao B ={4;5}
1.
a) A = 3^1 + 3^2 +........+3^2006
3A = 3^2 + ............+3^2006 + 3^2007
3A - A = (3^2 +........+3^2006 +3^2007)-(3^1 + 3^2+.....+3^2006)
2A = 3^2007 - 3^1
a) 23 . 17 - 23 . 14
= 23(17-14)
=23. 3= 24
b) 80 - ( 4 . 5 - 3 . 23 )
= 80- 22. (5-3.2)= 80- 22.(-1)
= 80- 4.(-1)= 80- (-4)= 84
c) 35 - { 12 - [ -14 + ( -2) }
= 35 - { 12 - (-16) }
=35- 28= 7
d) 49 - ( -45) - 23
= 94-23= 71
e) 13 - 18 - ( -42) - 15
= -5 -(-42) -15
= -20+42= 22
g) -452 - ( -67 + 75 - 452 )
= -452- (8-452)
= -452 -(- 444)= -8
h) |31−17|−|13−52|
= 14- 39= -25
80 -(4.52 -3.23)
= 80- (4.25- 3.8)
= 80- (100-24)
= 80-76= 4
a)= \(2^3\left(17-14\right)\)
\(=8.3\)
\(=24\)
b)\(=17\left(85+15\right)-120\)
\(=17.100-120\)
\(=1700-120\)
\(=1580\)
c)\(=\left(25.4\right).\left(125.8\right).\left(2.5\right)\)
\(=100.1000.10\)
\(=1000000\)
d)\(=24.53+24.87-24.40\)
\(=24\left(53+87-40\right)\)
\(=24.100\)
\(=2400\)
e)\(=5.7.77-7.60-7.7.25-15.6.7\)
\(=7\left(5.77-60-7.25-15.6\right)\)
\(=7\left(385-60-175-90\right)\)
\(=7.60\)
\(=420\)
1. a) 17.85 + 15.17 - 120
= 17.( 85 + 15) - 120
= 17. 100 -120
= 1700 - 120
= 1580
b) 20 - [ 30 - (5 - 1)2 ]
= 20 - [ 30 - 42 ]
= 20 - [ 30 - 16 ]
= 20 - 14
= 6
2. a) 70 - 5.(x - 3) = 45
5.(x - 3) = 70 - 45
5.(x -3) = 25
x - 3 = 25 : 5
x - 3 = 5
x = 5 + 3
x = 8
b) 10 + 2.x = 45 : 43
10 + 2.x = 42
10 + 2.x = 16
2.x = 16 - 10
2.x = 6
x = 6 : 2
x =3
1)a:17.85+15.17-120=17.(85+15)-120=17.100-120=1700-120=1580
b: 20-[30-(5-1)^2 = 20-[30-4^2]=20-(30-16)=20-15=5
2)
a: 70-5(x-3)=45
5(x-3) = 70-45=25
x-3 = 25:5=5
x= 5+3=8
b: 10+2x = 4^5:4^3
10+2x = 4^2
10+2x = 16
2x = 16-10=6
x = 6:2=3
a, 53 * 39 + 47 * 59 - 53 * 21 - 47 * 21 c, (43 * 52 - 43 ) : ( 4 * 42 )
= ( 53 + 47 ) * 39 - ( 53 + 47 ) * 21 = ( 64 * 25 - 64 ) : ( 4 * 16 )
= 100 * 39 - 100 * 21 = ( 1600 - 64 ) : 64
= ( 39 - 21 ) * 100 = 1536 : 64
= 18 * 100 = 24
= 1800
CÂU 1
\(5^{n+1}+5^n=750\)
\(=>5^n\cdot5+5^n=750\)
\(=>5^n\cdot\left(5+1\right)=750\)
\(=>5^n\cdot6=750\)
\(=>5^n=750:6\)
\(=>5^n=125\)
\(=>5^n=5^3\)
\(=>n=3\)
a) 25 - [ 49 - (23 x 3 ) ]
= 25- [ 49 - 24 ]
=0
a ) 25 - [ 49 - ( 23 . 17 - 23 . 14 ) ]
= 25 - { 49 - [ 23 ( 17 - 14 ) ]
= 25 - [ 49 - ( 23 . 3 ) ]
= 25 - ( 49 - 24 )
= 25 - ( 49 - 16 )
= 25 - 33
= - 8