Question

Find the 25th term of the AP `5, 4 1/2, 4, 3 1/2, 3,`....

Answer 1

The given AP is `5, 4 1/2, 4, 3 1/2, 3,`....

First term = 5

Common difference = `4 1/2 - 5`

⇒ `9/2 - 5`

⇒ `(9 - 10)/2 = -1/2`

∴  a = 5 and d = `-1/2`

Now, T₂₅ = a + (25 – 1)d 

= a + 24d

= `5 + 24 xx (-1/2)`

= 5 – 12

= –7

∴ 25^th term = –7