Given the Functions
[tex]\begin{gathered} f(x)=5x+5 \\ g(x)=6x^2 \end{gathered}[/tex]Find: (fg)(x).
It's required to find the product of f and g, thus:
[tex]\begin{gathered} (fg)(x)=(5x+5)(6x^2) \\ (fg)(x)=30x^3+30x^2 \end{gathered}[/tex]The domain of this function is the set of all real numbers because x can take any real value and the function will exist, thus the answer is (third choice):
[tex]\begin{gathered} 30x^3+30x^2 \\ \text{Domain: } \\ (-\infty,+\infty) \end{gathered}[/tex]