Gujarat BoardEnglish MediumSTD 11 ScienceMATHSArithmetic Progressions2 Marks
Question
Find the sum of first n natural numbers.
✓
Answer
A.P. formed is 1, 2, 3, 4, ..., n. Here, $\text{a}=1$ $\text{d}=1$ $\text{l}=\text{n}$ So sum of n terms $=\text{s}_\text{n}=\frac{\text{n}}{2}[2\text{a}+(\text{n}-1)\text{d}]$ $=\frac{\text{n}}{2}[2+(\text{n}-1)1]$ $=\frac{\text{n}(\text{n}+1)}{2}$ is the sum of first n natural numbers.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.