Question

find sum of 1st 10 odd natural number .​

Answer 1

$Question :-find sum of 1st 10 odd natural number .​\\Answer :-\\ The sum of 1^{st} 10 odd natural number are :-\\1 , 3 , 5 ,7 , 9 ,.........\\where , \\ a = 1\\ d = 3 - 1 = 2\\ n = 10 \\\\therefore :- \\ a_{n} = a + ( n - 1 )d\\ a_{n} = 1 + ( 10-1)2\\ a_{n} = 19\\therefore :-,\\ s_{n} = \frac{n}{2} ( a + a_{n}\\ = 5 ( 1+19)\\ = 100\\\\thank you$

thank you