Question

and the sum of first 20 terms of the series 4 + 7 + 10 + ...........​

Answer 1

a=7 d=3 n=20

Sn=20/2(2*4+(20-1)3))

Sn=10(8+19*3)

Sn=10(65)

Sn=650

Answer 2

Answer:

650

Step-by-step explanation:

sum of n term in ap is n/2 (2a+(n-1)d)

from given series a=4,d=3

Sn=20/2(4(2)+(20-1)3)

=10(8+19(3))

=10(8+57)

=10(65)

650