Question

find the above value​

Answer 1

Answer:

Because, the period of function f(x) is 7

Therefore,

f(x+8) = f(x+1)

So, everywhere in the first row of the determinant you'll have f(x+1) to be taken as common and out of the determinant, and hence because f(x+1) wouldn't be identically zero that means the determinant should be equal to 0.

The determinant will be

1. 1. 1.

1. 2. -5

2. 3. lambda.

This determinant must be zero and hence now you can easily find the value of lambda from here.

Sorry I'm very lazy to find out the value further .

Hope this helps you ! ｡◕‿◕｡