Question

find the sum of the first twenty terms of arthematic series 2+7+2+.. using formula​

Answer 1

Step-by-step explanation:

We know, Sum of n terms is S

n = n/ [2a+(n−1)d]

a= First term =2

d= Common difference =7−2=5

n= number of terms =20

S = 20/2[2(2)+(20−1)5]

S

20

=10[4+95]

S

20

=10(99)

S

20

=990

Answer 2

state the question clearly