Question

For
an A.P , findsS if a=7 and d=5​

Answer 1

Answer:

a=-7

d=5

T12=?

T12=a+(n-1)d

T12=-7+(12-1)5

T12=-7+11*5

T12=-7+55

T12=48

Therefore the 12th term of an AP is 48

Answer 2

Answer:

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

Sn=n/2(14+(n-1)5)

Sn=n/2(9+5n)