(Q21).In an AP:
(iii) Given a
12
= 37, d = 3 find a and S
12
.
Given :
a
12
= a +
d =
⇒ a +
=
⇒ a =
–
=
Now, S
n
=
n
2
(a + l)
S
12
=
2
(
+
)
=
×
=
Clear