Question

which term of the A.P. 150, 147, 144,......is its first negative term ?

Answer 1

n51
so, n= 52
verifying
a =150 + 51*-3
=150-153
=-3
look do not use equal to but the sign that comes when u press shift+comma
that is the greater to sign , zero should be greater .
So 52 is the answer

Answer 2

given,

a = 150 , d = 147 - 150 =-3.

an = a+(n-1)d,
= 150+(n-1)×(-3)
=150-3n+3
an= 153 - 3n.

we have to find first -ve term of this AP

therefore, an < 0
153 - 3n < 0
153 < 3n
n = 153/3
n = 51.
51th term of AP will the first -ve term