a_n = n^2 + 3 n

常见问题解答

• 写出前六项 \(a_{n} = n^{2} + 3 n\)

  

  $$4,10,18,28,40,54$$

• 判断该数列是否为等差数列 \(a_{n} = n^{2} + 3 n\)

  

  $$\text{不是等差数列}$$

• 判断该数列是否为等比数列 \(a_{n} = n^{2} + 3 n\)

  

  $$\text{不是等比数列}$$

• 找到极限 \(a_{n} = n^{2} + 3 n\)

  

  $$+\infty$$

• 确定收敛或发散 \(a_{n} = n^{2} + 3 n\)

  

  $$\text{发散}$$