Question

Question 3 (i)
In an AP:
(i) Given a = 5, d = 3, $a_n=50$, find n and $S_n$.

Answer 1

(i)
$Giventhat,a=5,d=3,a_n=50As{a}_n=a+(n-1)d,\Rightarrow 50=5+(n-1)\times 3\Rightarrow 3(n-1)=45\Rightarrow n-1=15\Rightarrow n=16Now,S_n=\frac{n}{2}(a+a_n)S_n=\frac{16}{2}(5+50)=440$