If the sum of n terms of two series of A.P are in the ratio
5n+4:9n+6 .find the ratio of their 13th terms

Answer Posted / akshay b menon

(5n+4)/(9n+6)=((n/2){2x+(n-1)d})/((n/2){2x'+(n-1)d'})
             =(2x+(n-1)d)/(2x'+(n-1)d')  
             =(x+{(n-1)/2}d)/(x'+{(n-1)/2}d')
         implies,
             m=(n-1)/2
             2m-1=n
          since m=13,n=25
          substituting value of n in given ratio
            (5*25+4)/(9*25+6)=129/231

Is This Answer Correct ?    45 Yes 47 No



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