f(x) = 1- sqrt 4-x?

Question

please explain

Answer 1

f ( x ) = 1 - (4 - x)^(½)
But I wonder what you are asking?
Do you want f `(x) perhaps?
If so:-
f `(x) = (- 1/2)(4 - x)^(-1/2) (-1)
f ` (x) = 1/ [ 2 (4 - x)^(1/2) ]