Find the sum using the appropriate formula to the given term. 3 + 6 + 9 +... : S10
Mathematics · High School · Thu Feb 04 2021
llm
Answered on
We have,
3 + 6 + 9 +...
Here a = 3
d = a2 - a1
= 6 - 3
= 3
n = 10
Formula :
Sn = n/2[ 2a + (n-1)d]
S10 = 10/2[2×3 + (10-1)×3]
= 5[6 + 9×3]
= 5[6 + 27]
= 5[33]
= 165
Hence, sum of first 10 terms (S10) is 165.