Which term of the A.P. is its first negative term?
a = 121, d = -4
An = -ve
An= a + (n – 1) d
= 121 + (n – 1) -4
= 125 – 4n
Since, we want –ve term
Therefore, 4n should be a number greater than 125
Hence, 128 is the number greater than 125 and divisible by 4
4n = 128
n = 32
Therefore, 32nd term of the given A.P. is –ve