Question

in A.P. a= 10,d= 4 nth term= 38 ,find n and Sn?
please answer fast if u know the answer ​

Answer 1

Answer:

n=8

sn=192

Step-by-step explanation:

given,

a=10

d=4

an=38

as we know that,

an=a+(n-1)*d

38=10+(n-1)*4. (putting the values)

28=(n-1)*4

7=n-1

8=n.

sn=n/2(a+an)

sn=8/2(10+38)

sn=4(48)

sn=192.