Which term of the AP: 121, 117, 113, . . ., isits first negative term?

Here; a = 121 and d = -4

The first negative term will be less than zero. Moreover, each term gives 1 as remainder when divided by 4. So the last positive term should be5.

Let us check the value of n for an = 5.

5 = a + (n – 1)d

121 + (n – 1) (- 4) = 5

121 – 4n + 4 = 5

125 – 4n = 5

4n = 120

n = 30

Thus, a₃₁ = 5 – 4

= 1

Therefore, 32nd term will be the first negative term.