Question

Find the sum of first $24$ terms of A.P $5,8,11,14,...$

Answer 1

Formula:

$S_n=\frac{n}{2}[2a+(n-1\left)d\right]$

Given,

$S_{24}=\frac{24}{2}\left[2\right(5)+(24-1\left)3\right]$

$=12[10+23\times 3]$

$=948$