The sum of first 'n' terms of an A.P is 5n^2+3n.if its nth term is 168.find n.also find the 20th term pf the A.P.
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s1 = a1 = 5+3 = 8
a2 = s2 - s1 = 26 - 8 = 18
d = a2 - a1 = 10
an = 168
168 = 8+(n-1)10
160=10(n-1)
n=17
a20 = 8 + 190 =198
here is ur answer hope it helped XD
a2 = s2 - s1 = 26 - 8 = 18
d = a2 - a1 = 10
an = 168
168 = 8+(n-1)10
160=10(n-1)
n=17
a20 = 8 + 190 =198
here is ur answer hope it helped XD
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