Question

find first negative term from following A.P.
122,116,110,....
(Note: find smallest n such that tn<0.

Answer 1

A.P is 122,116,110,....
a=122
d==-6
Let an=0
Now by a(n )formula.

122+(n-1)-6=0
122-6n+6=0
6n=128
n=21.33
Therefore n is 22nd term.

a(22)=a+21d
=122+21*-6
=122-126
=-4
So -4 is first -ve term.

Answer 2

as a= 122 & d= -5
So by applying the formula of an then n comes out to be 25.5
So the first negative term is the 26th term