Which of the term of A.P. 5, 2, -1, … is -49 ?( 9th term, 11th term, 19th term )
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Answered by
1
Answer:
19 term is your answer ok
Answered by
0
Answer:
- 49 is the 19th term of the AP.
Step-by-step-explanation:
The given AP is 5, 2, - 1,....
- t₁ = a = 5
- d = t₂ - t₁ = 2 - 5 = - 3
- tₙ = - 49
We know that,
tₙ = a + ( n - 1 ) * d
⇒ - 49 = 5 + ( n - 1 ) * ( - 3 )
⇒ - 49 = 5 - 3n + 3
⇒ - 49 - 5 = - 3n + 3
⇒ - 54 = - 3n + 3
⇒ - 54 / 3 = ( - 3n / 3 ) + 3 / 3
⇒ - 18 = - n + 1
⇒ - 18 - 1 = - n
⇒ - n = - 19
⇒ n = 19
∴ - 49 is the 19th term of the AP.
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