Answers

2016-02-11T19:57:00+05:30
A.n.=78
a=3
d=5
find =n
A.n = a+d(n-1)
78 =3+5(n-1)
78-3=5(n-1)
75/5=n-1
15+1=n
n=16
1 5 1
2016-02-11T19:57:04+05:30
Givenan=78,a1=3,a2=8
d=a2-a1
d=8-3
d=5
an=a+(n-1)d
78=3+(n-1)5
78-3=(n-1)5
75/5=(n-1)
15+1=n
n=16
therfore 78 is the 16th term of the given A.P
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