Question

The sum of first 20 terms of the
A.P.12,15,18,....is समांतर श्रेणी
12,15,18,.... के प्रथम 20 पदो का योग है।​

Answer 1

Answer:

we have a = 12

d = 3

n = 20

now we know that

Sn = n/2( 2a + (n-1)d)

S20 = 20/2(2×12+(20-1)3)

= 10(24 + 47)

= 10(71)

=. 710