Q19 of 167 Page 20

Mark the correct alternative in the following:

If, is the sum of an arithmetic progression of ‘n’ odd number of terms and the sum of the terms of the series in odd places, then


Here, First A.P is 1,3,5…


So, a=1 and d=3-1=2


Now, sum of n term is given by,







Now, second A.P. is 1,5,9,…


In this A.P. a=1, d=5-1=4


Let us assume that total no. of term in first A.P. is even then total no. of term in second A.P. is


Now,



)




Then



Let us assume that total no. of term in first A.P. is odd then total no. of term in second A.P. is


Now,



)




Then


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