A=\(\frac{2.6.10+6.10.14+...+194+198+202}{1.3.5+3.5.7+...+97.99.101}\)\(=\frac{2.2.2\left(1.3.5\right)+2.2.2\left(3.5.7\right)+...+2.2.2\left(97.99.101\right)}{1.3.5+3.5.7+...+97.99.101}\)

\(=\frac{2.2.2\left(1.3.5+3.5.7+...+97.99.101\right)}{1.3.5+3.5.7+...+97.99.101}\)\(=\frac{2.2.2}{1}=8\)

Ta có : 

\(2222:2222=1\)

\(2222:1111=2\)

\(2222:740=3\left(dư2\right)\)

\(2222:555=4\left(dư2\right)\)

\(2222:370=6\left(dư2\right)\)

\(2222:317=7\left(dư3\right)\)

\(2222:277=8\left(dư6\right)\)

\(2222:246=9\left(dư8\right)\)

\(2222:222=10\left(dư2\right)\)

k mình nhé !!!!!

Ko phia nhu the dau vi du nhu the nay nay  vd : 2×2-2×2 day nhu the day

To chua duoc cho cau dau sorry nhung bai  cau sai roi ban a

, mình giải cho

giai kieu gi co giang cho minh di

 1+2+3+4+5+6+7.......17+18+19+20=(29+1)×(20:10)

=21×10

=210

1 + 9 + 2 + 8 + 3 + 7 + 4 + 6 + 5 + 5 + 6 + 4 + 7 + 3 + 8 + 2 + 9 + 1

= 10 + 10 + 10 +10 +10 + 10 + 10 + 10 + 10

= 10 x 9

= 90

1+9+2+8+3+7+4+6+5+5+6+4+7+3+8+2+9+1

=10+10+10+10+10

=50

Đặt S = 1 x 2 + 2 x 3 + ..... + 9 x 10

3S = 1 x 2 x (3-0) + 2 x 3 x (4 - 1) + ....... + 9 x 10 x (11 - 8)

3S = 1 x 2 x 3 + 2 x 3 x 4 - 1 x 2 x 3 + ......... + 9 x 10 x 11 - 8 x 9 x 10

3S = ( 1 x 2 x 3 -1 x 2 x 3) + ( 2 x 3 x4 - 2 x 3 x 4) + ..... + (8 x 9  x 10 - 8 x 9 x 10) + 9 x 10 x 11

3S = 9 x 10 x 11 = 990

S = 990 : 3 = 330     

A=1/1*2+1/2*3+...+1/9*10

=1-1/2+1/2-1/3+...+1/9-1/10

=(1-1/10)+(1/2-1/2)+...+(1/9-1/9)

=(10/10-1/10)+0+...+0=9/10

\(A=\frac{1}{1.2}+\frac{1}{2.3}+...+\frac{1}{9.10}=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{9}-\frac{1}{10}=1-\frac{1}{10}=\frac{9}{10}\)

Ta có: 1+2+3+…+20=20.(20+1):2=20.21:2=420:2=210

khoảng cách: 2-1=1

số số hạng là: (20-1):1+1=20(số)

tổng là: (20+1)x20:2=210

Đáp số : 210

k cho mình nha