if the sum of first n terms of an AP is given by Sn=3nsquare+ 2n,find the nth term of the AP
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Sn = 3n^2 +2n
putting value of n = 1, we get
Sn= 3(1)^2 + 2 (1)
= 3+2= 5 = a1 (first term)
putting value of n= 2
= 3(2)^2+2(2)
12+4=16
a1+ a2 = S2
5+a2 = 16
a2= 16 minus 5 = 11
a2 minus a1 = d (common difference)
11 minus 5 =6
now a1=5and d=6
now you can find the nth term.
putting value of n = 1, we get
Sn= 3(1)^2 + 2 (1)
= 3+2= 5 = a1 (first term)
putting value of n= 2
= 3(2)^2+2(2)
12+4=16
a1+ a2 = S2
5+a2 = 16
a2= 16 minus 5 = 11
a2 minus a1 = d (common difference)
11 minus 5 =6
now a1=5and d=6
now you can find the nth term.
palakhanduja:
hey just put the values you will not get the value of n as a whole number.
you will get 5+ (n-1) 6, 5+6n-6 ,6n-1
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