It just means to isolate a. You can start like this::
V^2 = U^2 + 2AS
V^2 - U^2 = 2AS
(V^2 - U^2)/2S = A
A= (V^2 - U^2)/2S
Hello,
As said T is the point of intersection of f and g, this means that there are only one point and that k=+1.
So dom f=

(x>0)
For e2020 the answer is C