Question

If the 3rdand the 9th terms of an AP are 4 and -8 respectively which term of this AP is zero ​

Answer 1

Answer:

Given:

3rd term of an AP = 4

9th term = - 8

We know that,

nth term of an AP [ a(n) ] = a + (n - 1)d

Hence,

a + (3 - 1)d = 4

→ a + 2d = 4 -- equation (1)

a + (9 - 1)d = - 8

→ a + 8d = - 8 -- equation (2)

Subtracting equation (1) from (2) we get,

→ a + 8d - (a + 2d) = - 8 - 4

→ a + 8d - a - 2d = - 12

→ 6d = - 12

→ d = - 12/6

→ d = - 2

Substitute the value of "d" in equation (1)

→ a + 2d = 4

→ a + 2( - 2) = 4

→ a - 4 = 4

→ a = 4 + 4

→ a = 8

We have to find the term which is zero.

Hence,

a + (n - 1)d = 0

→ 8 + (n - 1) * ( - 2) = 0

→ 8 - 2n + 2 = 0

→ 10 - 2n = 0

→ 10 = 2n

→ n = 10/2

→ n = 5

Hence, 0 is the 5th term of the given AP.

Answer 2

Answer:

5th term of the AP will be 0

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