Question

if 3rd and 9th term of an ap are 4 and minus 8 respectively which term of this ap is zero​

Answer 1

Answer:

The answer has been given in above attachment

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Answer 2

Answer:

$\tt{a_{3} = 4}$

a + 2d = 4

a = 4 - 2d ..(1)

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$\tt{a_{9} = (-8)}$

a + 8d = -8

a = -8 - 8d ..(2)

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(1) = (2):

4 - 2d = -8 - 8d

12 = -6d

d = -2

--

a = 4 - 2d

a = 4 - 2(-2)

a = 4 + 4

a = 8

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When $\tt{a_{n} = 0}$:

a + (n - 1)d = 0

8 + (n - 1)(-2) = 0

8 - 2n + 2 = 0

2n = 10

n = 5

--

Thus, 5th term is 0

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