Find the functional values requested in the problem

F(x)=x^2-t^2

(a) F(t) =
(b) F(4t) =

F(x)=x^2-t^2

then

F(t)=t^2-t^2=0
F(4t)=(4t)^2-t^2=15t^2

Find the functional values requested in the problem.
F(x)=x^2-25t^2
(a)F(5t)=
(b)F(6t)=

Please help me with this