Answer:
All Real numbers
Step-by-step explanation:
c(x)= x-3
d(x) = x+3
dc(x)= (x-3)(x+3)
[tex](a+b)(a-b)=(a^2-b^2)[/tex]
[tex]dc(x) = (x^2-9)[/tex]
[tex]x^2-9[/tex] is defined for all values of x , And hence the domain of cd(x) will be set of all Real Numbers
