Q. 15 C5.0( 3 Votes )

# Find the 12^{th} term from the end of the following arithmetic progression:

1, 4, 7, 10, … 88

Answer :

A.P is known for Arithmetic Progression whose common difference = a_{n} – a_{n-1} where n > 0

a = a_{1} = 1, a_{2} = 4, l = 88

Common difference, d = a_{2} – a_{1} = 4 – 1 = 3

We know, n^{th} term from end, b_{n} = l – (n – 1)d where l is last term or a_{1} and d is common difference and n is any natural number

∴ b_{12} = 88 – (12 – 1)3

⇒ b_{12} = 88 – 36 + 3

⇒ b_{12} = 91 – 36

⇒ b_{12} = 55

Hence, 12^{th}term from end for the given A.P is 55

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