# T19 = ? for the given A.P., 9, 4, −1, −6 ........ Activity :- Here a = 9, d = □ tn = a + (n − 1)d t19 = 9 + (19 − 1) □ = 9 + □ = □ - Algebra

Sum

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

Activity :- Here a = 9, d = square

tn = a + (n − 1)d

t19 = 9 + (19 − 1) square

= 9 + square

= square

#### Solution

Here a = 9, d = 4 - 9 = − 5

tn = a + (n − 1)d

t19 = 9 + (19 − 1) − 5

= 9 + 18(-5)

= 9 + − 90

= − 81

Concept: Arithmetic Progression
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