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Tìm x
a.( x - 140 ) : 3 = 27
x - 140 = 27 . 3
x - 140 = 81
x = 221
b.14 - 4 ( x + 1 ) = 10
4 ( x + 1 ) = 14 - 10
4 ( x +1) = 4
x + 1 = 1
x = 0
c. 15 ( 7 - x ) = 15
7 - x = 1
x = 6
d.34 ( x - 3 ) = 0
\(\Rightarrow\) 34 = 0 hoặc x - 3 = 0
1. 34 = 0 ( vô lí )
2. x - 3 = 0 \(\Rightarrow\) x = 3
e. 24 + 6 (3 - x ) = 30
6( 3- x ) = 30 - 24
6( 3 - x ) = 6
3 - x = 1
x = 2
f. x3 + 24 = 51
x3 = 51 - 24
x3 = 27
\(\Rightarrow\)x = 3 ; x = -3
g. ( x- 5 )2 - 5 = 44
( x - 5) 2 = 49
\(\Rightarrow\)x - 5 = 7 hoặc x - 5 = -7
1. x - 5 = 7\(\Rightarrow\)x = 12
2. x - 5 = -7 \(\Rightarrow\)x = -2
h. ( x + 1 )3 - 23 = 4
( x + 1 )3 =27
\(\Rightarrow\) x + 1 = 3 hoặc x + 1 = -3
1. x + 1 = 3\(\Rightarrow\)x = 2
2. x + 1 = -3 \(\Rightarrow\)x = -4
a) 47 - [(45.16 - 25.12 ) : 14]
= 47 - [ (720 - 300 ) : 14
= 47 - [ 420 : 14 ]
= 47 - 30
= 17
b) 50 - [ (20 - 8 ) : 2 + 34 ]
= 50 - [ 12 : 2 + 34 ]
= 50 - [ 6 + 34 ]
= 50 - 40
= 10
c) 100 - [ 60 : ( 15625 : 625 - 15 )
= 100 - [ 60 : ( 25 - 15 ) ]
= 100 - [ 60 : 10 ]
= 100 - 6
= 94
d)50-[(50-235)/2+3
=50-(10/2+3)
=50-8
=42
minh chi giupban duoc den do thoi ha
a) 27^16 : 9^10
Ta có: (3.9)^16 : 9^10
= 3^16.9^16: 9^10
= 3^16. 9^6
= 3^16.(3^2)^6
=3^16.3^12
=3^28
a) \(A=1+2+2^2+2^3+...+2^{60}\)
=>\(2A=2+2^2+2^3+2^4+...+2^{61}\)
=>\(2A-A=\left(2+2^2+2^3+2^4+...+2^{61}\right)-\left(1+2+2^2+2^3+...+2^{60}\right)\)
=>\(A=2^{61}-1\)
b) \(B=1+3+3^2+3^3+...+3^{46}\)
=>\(3B=3+3^2+3^3+3^4+...+3^{47}\)
=>\(3B-B=\left(3+3^2+3^3+3^4+...+3^{47}\right)-\left(1+3+3^2+3^3+...+3^{46}\right)\)
=>\(2A=3^{47}-1\)
=>\(B=\frac{3^{47}-1}{2}\)
c) \(C=1+5^2+5^4+...+5^{200}\)
=>\(5^2C=5^2+5^4+5^6+...+5^{202}\)
=>\(25C=5^2+5^4+5^6+...+5^{202}\)
=>\(25C-C=\left(5^2+5^4+5^6+...+5^{202}\right)-\left(1+5^2+5^4+...+5^{200}\right)\)
=>\(24C=5^{202}-1\)
=>\(C=\frac{5^{202}-1}{24}\)
a) A = \(1+2+2^2+2^3+...+2^{60}\)
2A = \(2.\left(1+2+2^2+2^3+...+2^{60}\right)\)
2A = \(2+2^2+2^3+2^4+...+2^{61}\)
2A - A = \(\left(2+2^2+2^3+2^4+...+2^{61}\right)\)- \(\left(1+2+2^2+2^3+...+2^{60}\right)\)
A = \(2^{61}-1\)
b)B = \(1+3+3^2+3^3+...+3^{46}\)
3B = \(3.\left(1+3+3^2+3^3+...+3^{46}\right)\)
3B = \(3+3^2+3^3+3^4+...+3^{47}\)
3B - B = \(\left(3+3^2+3^3+3^4+...+3^{47}\right)\)- \(\left(1+3+3^2+3^3+...+3^{46}\right)\)
2B = \(3^{47}-1\)
B = \(\left(3^{47}-1\right):2\)
2B = 2^2 +3^2+4^2 + ....+51^2
2B-B= 2^2+3^2+4^2+....+51^2 - 1^2 +2^2 + 3^2 +....+50^2
B= 51^2-1^2
= 50^2
=2500
2C = 3^2+4^2+......+ 51^2
2C-C= 3^2+4^2+....+51^2-2^2+3^2+.....+50^2
C= 51^2-2^2
C= 49^2
2D=2^2+3^2+4^2+......+ 50^2
2D-D= 2^2+3^2+......+50^2-1^2+2^2+....+49^2
D= 50^2- 1^2
D= 49^2
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