Given: f: x → \(\sqrt{x}\) and g : x → 25 - x\(^2\),

f o g(3) means replace x with g(3) in f: x → \(\sqrt{x}\)

f: x → \(\sqrt{x}\) = f : g(3) → \(\sqrt{x}\)

but, g(3) → 25 - 3\(^2\), = 25 - 9 = 16

f o g(3) → \(\sqrt{g(3)}\) = \(\sqrt{16}\) = 4.