S=1 + 3 + 5 + ... + 99 + 101

=> S = ( 101 + 1 ) . 51 : 2

=> S = 102 . 51 ; 2

=> S = 5202 : 2

=> S = 2601

Ta có: 1+3+5+...+99+101

Tổng trên là:(1+101).2= 204

Đ/S: 204

k cho mk nha!!!!

6.7.168 – 14.85.3 + 17.21.2

= 42 . 168 - 42 . 85 + 42 . 17

= 42 . ( 168 - 85 + 17 )

= 42 . 100

= 4200

= 2.3.7.168 - 2.7.85.3 + 17.2.21

= 21.336 - 21.170 + 21.34

= 21.( 336 + 34 - 170 )

= 21.200

= 4200

( 57 - 3 × X ) × 12 - 24 = 47 × 2 - 82

( 57 - 3 × X ) × 12 - 24 = 94 - 82

( 57 - 3 × X ) × 12 - 24 = 12

( 57 - 3 × X ) × 12 = 12 + 24

( 57 - 3 × X ) × 12 = 36

57 - 3 × X = 36 : 12

57 - 3 × X = 3

3 × X = 57 - 3

3 × X = 54

      X = 54 : 3

      X = 18

( 57 - 3 × X ) × 12 - 24 = 47 × 2 - 82

= ( 57 - 3 × X ) × 12 - 24 = 94 - 82

= ( 57 - 3 × X ) × 12 - 24 = 12

= ( 57 - 3 × X ) × 12 = 12 + 24

= ( 57 - 3 × X ) × 12 = 36

= 57 - 3 × X = 36 : 12

= 57 - 3 × X = 3

= 3 × X = 57 - 3

= 3 × X = 54

      X = 54 : 3

      X = 18

cảm ơn

5 số 5 : (5+5) ⁵  . (5+5)

2.x² = 18

 x² = 18 : 2

x² = 9

x² = 3²

\(\Rightarrow\)x = 3

( 2⁰ + 2¹ + 2² ) . x - 3 = 18

=> ( 1 + 2 + 4 ) . x = 21

=> 7 . x = 21

=> x = 21 : 7 = 3

2 . x² = 18

=> x² = 9

=> x² = 3² = ( -3 )²

\(\Rightarrow\orbr{\begin{cases}x=3\\x=-3\end{cases}}\)

Trả lời :

a) 8³ = ( 2³ )³ = 2⁹

b) 3⁹ 

c) 5³

~~Học tốt~~

2 . 29 . 3 + 6 . 71 + 120

= 6 . 29 + 6 . 71 + 6 . 20

= 6 . ( 29 + 71 + 20 )

= 6 . 120

= 720

Tính nhanh:

2 . 29 . 3 + 6 . 71 + 120

( 29 + 71 ) + 120 + ( 3 + 6 . 2 )

100 + 120 + 36

220 + 36 

256