Let an be an arithmetic progression with a4 + a7 + a10 = 17 and a4 + a5 +···+ a13 + a14 = 77. if ak = 13, then k =?

The value of k is 18.

Step-by-step explanation:

Here, the AP is,

Let a be the first term and d is the common difference,

So the arithmetic sequence would be,

Given,

Now,

22 × equation (1) - 3 × equation (2),

We get,

From equation (1),

Here,

By substituting the value,

Hence, the value of k is 18.

irrational, cannot