Question

The sum of first five number is

Answer 1

Step-by-step explanation:

For finding this, we need to apply the formula :-

$\rm{S_n = \dfrac{n}{2} \times (2a + (n-1)d}$

• Where Sn is the sum
• Where n is the number of terms
• Where a is the first term
• And d is the common difference.

In this question -

• We need to find Sn
• We have n as 5
• We have d as 1
• We have a is 1.

So, apply the following :-

$\rm{S_n = \dfrac{n}{2} \times (2a + (n-1)d}$

$\rm{S_n = \dfrac{5}{2} \times (2(1) + (5-1)1}$

$\rm{S_n = \dfrac{5}{2} \times (2+ 4)}$

So, we get the final answer as 15. Hence, the required solution.