If sum of the first 11 terms of arithmetic progression equals that of the first 19 terms, then what is the sum of the first 30 terms?
Choose the correct choice from the following options:
A) 0  B) -1  C) 1  D) Not unique  E) None of these
Explanation :   Given,   t1 + t2 + ........t11 = t1 + t2 + ........t19 (for an AP)   =&gt; (11/2) [ 2a + (11-1)d = (19/2) [ 2a + (19-1)d ]   =&gt; 22 a + 110d = 28 a + 342 d   =&gt; 16 a + 232 d = 0   =&gt; 2a + 29 d = 0   =&gt; (30/2)[ 2a + (30-1)d = 0.   S30 terms = 0.   0nswer : 0
<result>A</result>
If sum of the first 11 terms of arithmetic progression equals that of the first 19 terms, then what is the sum of the first 30 terms?