Answer each of the following questions in one word or one sentence or as per exact requirement of the question:

If , find the value of x.

Given cos (sin^-1 2/5 + cos^-1 x) = 0

⇒ cos (sin^-1 2/5 + cos^-1 x) = cos (π/2)

⇒ sin^-1 2/5 + cos^-1 x = π/2

We know that sin^-1 x + cos^-1 x = π/2

∴ x = 2/5