Question

is the sum of the nth term of an ap is n²+3n then it's 20th term is??​

Answer 1

Answer:

42

Step-by-step explanation:

S1=n²+3n

1²+3×1=4

a1=4=S1

a2=s2_s1

s2=n²+3n

2²+3×2=10

a2=s2-s1

10-4=6

a2=6

a+a+d=10

2a+d=10

2×4+d=10

8+d=10

20th term

a+19d

4+19×2=42