Answer:
x = 20
Step-by-step explanation:
given f(x) = [tex]\sqrt{x-4}[/tex], we have to solve
[tex]\sqrt{x-4}[/tex] = 4
Square both sides
([tex]\sqrt{x-4}[/tex])² = 4²
x - 4 = 16 ( add 4 to both sides )
x = 20
As a check
[tex]\sqrt{20-4}[/tex] = [tex]\sqrt{16}[/tex] = 4 ← correct
