Question

Sum of n terms of a series is 3n²+ 5n; show that the terms
of the series from an A.P. which term of that series in 152 ?
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Answer 1

Answer:

So 25th term is 152.

Step-by-step explanation:

Sn=3n^2+5n

S1=a1=3(1)2+5(1)=8  

S2=3(2)2+5(2)=22  

S2=22=a1+a2  

a2=22-8=14  

d=a2-a1=14-8=6  

nth term value is 152,then what is n?  

nth term=a+(n-1)d

152=8+(n-1)6

152-8 / 6=n-1

144/6=n-1

24+1=n

n=25

So 25th term is 152.