Question

Complete the activity by filling the boxes, to find So, if the first term of an A.P. is 7 and
common difference 3.
a = 7, d = 3, S19 = ?
Sn= n/2 [ ? +(n - 1) d]
S19 = 19/2 [14 + (19 - 1) ? ]
= 19/2 × ?
= ? × ? = ?​

Answer 1

Answer:

a=7,d=3,S19=?

Sn=n/2[2a+(n-1)d]

S19=19/2[14+(19-1) 3]

=19/2×68

=19×34

=646