Question

if sn=n^2+4n be the sum to first n terms of an AP ,then write the 20th term of the AP.

pls give step by step explanation​

Answer 1

Step-by-step explanation:

Sn =n²+4n

t20 =S21 -S19

S21 =(21)² +4(21)

= 441+ 84

= 525

S19 = (19)² + 4(19)

= 361+ 76

= 437

t20 = 525 -437

t20 = 88