Question

What is the sum of all odd integers between 8 and 26

Answer 1

odd integers between 8 and 26
{ 9,11,13,15,17,19,21,23,25}...added = 153 <==

Answer 2

It's an arythmetic sequence:


`a_1=9;\ d=2;\ a_9=25\\\\S_n=(a_1+a_n)/(2)\cdot n\\\\S_9=(9+25)/(2)\cdot9=(34)/(2)\cdot9=17\cdot9=153\\\\Answer:\boxed{153}`