hello sir, this is soumik... i didnt understand solution to find the double meaning........of the sum from ap (didnt understand the part of double answer from ap) ,i am in 10,the question is as follows....please help me

Asked by soumik acharjee | 30th Dec, 2013, 09:44: PM

Expert Answer:

Consider the A.P. 63, 60, 57, ...
 
Here, a = 63 and d = -3
 
The sum of n terms is given as 693. We need to find 'n'.
 
We know that,
 
The nth term of the series is a + (n - 1)d.
 
Therefore,
 
When n = 22, we have
 
 
Adding 0 to 693 will not change the sum and therefore, the two answers that we are getting are correct.
 

Answered by Vimala Ramamurthy | 1st Jan, 2014, 09:38: AM

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