\(\left\{210:\left[16+3.\left(6+3.2^2\right)\right]\right\}-3\)

\(=\left\{210:\left[16+3.\left(6+3.4\right)\right]\right\}-3\)

\(=\left\{210:\left[16+3.\left(6+12\right)\right]\right\}-3\)

\(=\left\{210:\left[16+3.18\right]\right\}-3\)

\(=\left\{210:\left[16+54\right]\right\}-3\)

\(=\left\{210:70\right\}-3\)

\(=3-3\)

\(=0\)

có tất cả các chữ số là: (210-3)/3+1=7

Tổng:(210+3)*70/2=7455

(210-3)+1:3=66
Tính tổng: (210+3).66:2= 14058 

Lời giải:

$\frac{A}{2}=\frac{1}{2}-\frac{1}{6}-\frac{1}{12}-\frac{1}{20}-...-\frac{1}{420}$

$\frac{A}{2}=\frac{1}{2}-\left(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{420}\right)$

Xét:

$\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{420}=\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{20.21}$

$=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{20}-\frac{1}{21}$

$=\frac{1}{2}-\frac{1}{21}$

Do đó:

$\frac{A}{2}=\frac{1}{2}-(\frac{1}{2}-\frac{1}{21})=\frac{1}{21}$

$\Rightarrow A=\frac{2}{21}$

\(B=\frac{3}{1}+\frac{3}{3}+\frac{3}{6}+...+\frac{3}{210}\)

\(=\frac{6}{2}+\frac{6}{6}+\frac{6}{12}+...+\frac{6}{420}\)

\(=\frac{6}{1.2}+\frac{6}{2.3}+\frac{6}{3.4}+...+\frac{6}{20.21}\)

\(=6\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{20}-\frac{1}{21}\right)\)

\(=6\left(1-\frac{1}{21}\right)\)

\(=6.\frac{20}{21}=\frac{40}{7}\)

 \(=210+46+\left(-210\right)+\left(-26\right)\)

\(=[210+\left(-210\right)]+[46+\left(-26\right)]\)

\(=0+20\) 

 =20

7 - 2 10 + 7 + 2 10

= 5 - 2 . 2 . 5 + 2   - 5 + 2 . 2 . 5 + 2   = 5 - 2 2 - 5 + 2 2 = 5 - 2 - 5 + 2 = 5 - 2 - 5 + 2 = - 2 2

a ,   400 + 3 + 8 1000 = 400 + 3 + 0 , 008 = 403 + 0 , 008 = 403 , 008 b , 65 + 0 , 7 + 0 , 003 = 65 , 7 + 0 , 003 = 65 , 703 c , 210 + 5 + 0 , 35 = 215 + 0 , 35 = 215 , 35 d , 170 + 9 + 6 100 + 3 10 = 170 + 9 + 0 , 06 + 0 , 3 = 179 + 0 , 06 + 0 , 3 = 179 , 06 + 0 , 3 = 179.36

= 210 + 46 -210 -26

= (210 - 210 ) + ( 46 - 26 )

= 0 + 20

= 20 

Chúc bạn học giỏi ! Kết bạn với mình nha

\(=210+46-210-26\)

\(=\left(210-210\right)+\left(46-26\right)\)

\(=0+20\)

\(=20\)

210 + 46 + – 210 + – 26 = 210 + 46 + – 210 + – 26 = 210 + – 210 + 46 + − 26 = 0 + 20 = 20.

150:25+210:35+2³.3²

=6+6+8.9

=6+6+72

=12+72

=84