A = { xϵN| n<5}

A = {x | x ∈ ℕ ; x < 5} 

ctv olm có mặt ạ 

64⁷ = ( 4³)⁷ = 4²¹ vậy 64⁷ = 4²¹

3³⁶ = (3³)¹² = 27¹² > 5¹² vậy 3³⁶ > 5¹²

125⁵ =( 5³)⁵ = 5¹⁵ > 5¹² = (5⁴)³ = 625³ vậy 125⁵ > 625³

31¹¹ <  34¹¹  = (2.17)¹¹ <  2¹².17¹¹ = (2⁴)³.17¹¹ = 16³.17¹¹ < 17¹⁴

vậy 31¹¹ < 17¹⁴

a) 5² . ( 2⁴ - 12 +1 ) = 5² . ( 16 - 12 + 1 ) = 5³

b) 37 . 49 + 37 . 53 - 37 . 2

= 37 . ( 49 + 53 -2 ) = 37 . 100 = 3700

c) 5⁶ : 5⁴ = 5^6-4 = 5² = 25

d) 7⁹ . 7² : 7¹⁰ = 7¹¹:7¹⁰ = 7

e) ( 2 + 4 + 6 + ... + 100 ) ( 223 . 335335 - 335 . 223223 )

= ( 2 + 4 + 6 + ... + 100 ) . 0 = 0

2A=2²+2³+2⁴+2⁵+...+2¹⁰¹

A=2A-A=2¹⁰¹-2

3B=3+3²+3³+3⁴+...+3²⁰¹⁰

2B=3B-B=3²⁰¹⁰-1\(\Rightarrow B=\dfrac{3^{2010}-1}{2}\)

C; D tính tương tự

Tính : 5\12 + 3\4= 5/12 + 9/12 = 14/12 = 7/6

3\4 - 5\12 = 9/12 - 5/12 = 4/12 = 1/3

 2\9 -1\6 = 1/18

7\4 - 1\3 = 17 /12

7 + 3\4  = 31/4 

35\10 - 18\24  = 11/4                      6\24 - 6\36 = 1/12

29\36 - 9\24   = 31/72           9\21 + 6\49 = 27/49

5/12 + 3/4 = 7/6

3/4 - 5/12 =  1/3

2/9 - 1/6 = 1/18

7/4 - 1/3 = 17/12

7 + 3/4 = 31/4

35/10 - 18/24 = 11/4

6/24 - 6/36 = 1/12

29/36 - 9/24 = 31/72

9/21 + 6/49 = 27/49

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