Question

Which term of following A.P. is – 940.

50, 40, 30, 20........

Activity :- Here a = `square`, d = `square`, t_n = – 940

According to formula, t_n = a + (n – 1)d

– 940 = `square`

n = `square`

Answer 1

Here a = \[\boxed{50}\], d = 40 – 50 = \[\boxed{-10}\], t_n = – 940

According to formula, t_n = a + (n – 1)d

∴ − 940 = \[\boxed{50 + (n - 1)(-10)}\]

∴ – 940 = 50 – 10n + 10

∴ – 940 = 60 – 10n

∴ 10n = 60 + 940

∴ 10n = 1000

∴ n = `1000/10`

∴ n = \[\boxed{100}\]