Số ?
2 = 1 + ... 6 = 2 + ... 8 = ...+ 3 10 = 8 + ....
3 = 1 + ... 6 =...+ 3 8 = 4 + .... 10 = ...+ 3
4 = ...+ 1 7 = 1 + ... 9 = ...+ 1 10 = 6 + ...
4 = 2 + ... 7 = ...+ 2 9 = ...+ 3 10 = ...+ 5
5 = ...+ 1 7 = 4 + .... 9 = 7 +.... 10 = 10 + ...
5 = 3 +.... 8 = ...+ 1 9 = 5 + ... 10 = 0 + .....
6 = ...+ 1 8 = 6 + ... 10 = ...+ 1 1 = 1 + ....
Tính:
6 – 3 – 1 = … | 1 + 3 + 2 = … | 6 – 1 – 2 = … |
6 – 3 – 2 = … | 3 + 1 + 2 = … | 6 – 1 – 3 = … |
Tính:
1 + 3 + 2 = 6 - 3 -1 = 6 - 1 - 2 =
3 + 1 + 2 = 6 - 3 -2 = 6 - 1 - 3 =
Tính:
5 + 4 = … | 6 + 3 = … | 7 + 2 = … | 1 + 8 = … |
5 + 3 + 1 = … | 6 + 2 + 1 = …. | 7 + 1 + 1 = … | 1 + 2 + 6 = … |
5 + 2 + 2 =… | 6 + 3 + 0 = … | 7 + 0 + 2 = … | 1 + 5 + 3 = … |
Tính:
4 + 5 = 6 + 3 = 1 + 8 =
4 + 1 + 4 = 6 + 1 + 2 = 1 + 2 + 6 =
4 + 2 + 3 = 6 + 3 + 0 = 1 + 5 + 3 =
e,\(A=\frac{1}{2}+\frac{5}{6}+\frac{11}{12}+\frac{19}{20}+\frac{29}{30}+\frac{41}{42}=\left(1-\frac{1}{2}\right)+\left(1-\frac{1}{6}\right)+\left(1-\frac{1}{12}\right)+\left(1-\frac{1}{20}\right)+\left(1-\frac{1}{20}\right)+\left(1-\frac{1}{42}\right)\)
\(\Rightarrow A=1-\frac{1}{2}+1-\frac{1}{6}+1-\frac{1}{12}+1-\frac{1}{20}+1-\frac{1}{30}+1-\frac{1}{42}=4-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}\right)\)
\(\Rightarrow A=4-\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}\right)=4-\left(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}\right)\)
\(\Rightarrow A=4-\left(\frac{1}{1}-\frac{1}{7}\right)=4-\frac{6}{7}=3\frac{1}{7}\)
1+1+1+1+1=
2+3+4+2+3+4=
5+6+7+5+6+7+8=
9+9+9+9+1+1+1+1=