I WANT TO ASK 2 QUESTIONS

Asked by parmodgulati | 6th Feb, 2014, 05:41: PM

Expert Answer:

Consider the sum of 12 terms of an AP.
 
S subscript 12 equals 12 over 2 open parentheses 2 a plus 11 d close parentheses
Similarly, we have
 S subscript 8 equals 8 over 2 open parentheses 2 a plus 7 d close parentheses ; space space S subscript 4 equals 4 over 2 open parentheses 2 a plus 3 d close parentheses
Therefore,
S subscript 8 minus S subscript 4 equals 4 open parentheses 2 a plus 7 d close parentheses minus 2 open parentheses 2 a plus 3 d close parentheses equals 4 a plus 22 d rightwards double arrow 3 open parentheses S subscript 8 minus S subscript 4 close parentheses equals 3 cross times open parentheses 4 a plus 22 d close parentheses equals 6 open parentheses 2 a plus 11 d close parentheses equals S subscript 12
 
Kindly ask one question per query.

Answered by  | 7th Feb, 2014, 11:25: AM

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