Question

t₁₉ = ? for the given A.P., 9, 4, –1, –6......

Activity :- Here a = 9, d = `square`

t_n = a + (n – 1)d

t₁₉ = 9 + (19 – 1) `square`

= 9 + `square`

= `square`

Answer 1

Here a = 9, d = 4 – 9 = \[\boxed{-5}\]

t_n = a + (n – 1)d

t₁₉ = 9 + (19 – 1) \[\boxed{-5}\]

= 9 + 18(– 5)

= 9 + \[\boxed{-90}\]

= \[\boxed{-81}\]