Question

The first term of an AP is 3 and 11th term is 53 find s11

Answer 1

198 is the s11 term
here a is 3
we have t11=53
we can find the d by :
t11=a+(n-1)d
=3+(11-1)d
=we take d=3 so that we get t11=53
and then s11=n/2(a+l)
=11/2(3+33)
=198

Answer 2

hello users ........

we have given that:
 a = 3 
and
 $a_{11}$ = 53 

we have to find :
$S_{11}$ = ? 

solution :-
we know that :
$A_{n} = a + (n - 1) d$
and 
$S_{n} = \frac{n}{2} ( a + a_{n} )$

here,
$S_{11}$ =$\frac{11}{2} ( 3 + 53 )$

= $\frac{11 * 56}{2}$

= 11 * 28 = 308 answer 

@@ hope it helps @@