Question

"Question2
Aim-1 , Progressions ,Challengers .Page - 116
Which term of A. P is 7,3,-1 is -89"

Answer 1

`Given,`
A. P = 7 , 3 , -1 .

First term ( a) = 7
Common difference (d) = 3 - 7 = -4

We know that, P th term of an A.P = a + ( P - 1)d


Let -89 be the n th term,
-89 = a + ( n - 1 ) d
-89 = 7 + ( n - 1 ) (-4)
-89 = 7 -4n + 4
-89 = 11 - 4n .
4n = 11 + 89
4n = 100
n = 25

Therefore, For the Given A. P -89 is the 25 term.

Answer 2

Hey ❗❗
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↪Given AP :- 7 , 3 , -1

↪Formula an=a+(n-1)d

↪Given :-

↪a = 7

↪d = a2 - a1 = 3 - 7 = -4

↪an = -89 (let it be the last term )

↪Now put the values of a, d, an

↪7 + (n-1) - 4 = -89

↪7 - 4n + 4 = -89

↪7+ 4 - 4n = -89

↪11 - 4n = -89

↪-4n = -89 - 11

↪-4n = -100

↪n=100 / 4

↪n=25

↪Hence -89 is the 25th term

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