Question

Which term of the AP : 121, 117, 113,...... is the first negative term ?

[Hint : Find n for an < 0]​

Answer 1

Question :-

Which term of the AP : 121, 117, 113,...... is the first negative term ?

Solution :-

Given : 121, 117, 113, ........

★ a = 121

★ d = a2 - a1

= 117 - 121

= -4

Let the n th term be the first negative term of the given G.P.

Then, an < 0

⟹ an = a + (n - 1) d < 0

⟹ 121 + (n - 1) (-4) < 0

⟹ 121 - 4n + 4 < 0

⟹ 125 - 4n < 0

⟹ -4n < -125

⟹ 4n > 125

⟹ n > 125/4

⟹ n > 31.25

∴ When n = 32, the term becomes negative

(or)

32nd term is the first negative germ of the given A.P.

Answer 2

Answer:

32nd term

Step-by-step explanation:

a=121

d=-4

the last positive =1 ,then negative= -3

-3=121+(n-1)-4

-3=121-4n+4

4n=4+121+3

4n=128

n=32

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