Question

Find the sum of fit 42 terms of
the sesies :
-5, 0,5 ,10-------​

Answer 1

Answer:

We are giving that

a=-5,d=5,n =42

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

S42=42/2[2×5+(42-1)5]

=21(10+41×5)

=21(10+205)

=21×215

=4515