Question

Find the 23rd term from right end of the sequence 2,7,12,...127

Answer 1

Given A.P = 2, 7, 12, ..., 127

d = 7-2 = 5

Now,

an = a + (n-1)d

⇒127 = 2 + (n-1)5

⇒125 = (n-1)5

⇒25 = n-1

$\boxed{\bold{n = 26}}$

So, there are 26 terms in the A.P.

Now, 23rd term from the right = 26 - 23 term from the left = 3rd term from the left.

∴As already we have a₃ = 12, so the 23rd term from the right is 12.