The sum of first n natural numbers is:

1. $\dfrac{n(n − 1)}{2}$

2. $\dfrac{n(n + 1)}{2}$

3. $\dfrac{n(n + 2)}{2}$

4. $\dfrac{n(n − 2)}{2}$

The sum of first 50 natural numbers is:

1. 1050

2. 1175

3. 1225

4. 1275

The first term of an A.P. is 7 and the common difference is 3. The general term of the A.P. is:

1. T_n = 3n − 4

2. T_n = 2n + 5

3. T_n = 3n + 4

4. None of these

The 24th term of the A.P. −1, 3, 7, 11, … is:

1. 83

2. 87

3. 91

4. 95