Question

Find the sum of first 12 positive integers divisible by 9 by using progression method

Answer 1

Step-by-step explanation:

first 12 positive integers divisible by 9:-

9,18,27,36,45,54,63,72,81,90,99,108.

a(first term)=9

d(common difference)=9

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

S12=6[2x9+(12-1)9]

=> 6×117.

=> 702