Chapter 2, Functions - Section 2.7 - Combining Functions - 2.7 Exercises - Page 252: 7

$(f+g)(x)=3x \rightarrow$ $D=(-\infty,+\infty)$ $(f-g)(x)=-x \rightarrow$ $D=(-\infty,+\infty)$ $(f.g)(x)=2x^{2} \rightarrow$ $D=(-\infty,+\infty)$ $(\frac{f}{g})(x)=\frac{1}{2} \rightarrow$ $D=(-\infty,+\infty)$

We are given $f(x)=x$ and $g(x)=2x$ $(f+g)(x)=3x \rightarrow$ the domain is $(-\infty,+\infty)$ $(f-g)(x)=-x \rightarrow$ the domain is $(-\infty,+\infty)$ $(f.g)(x)=2x^{2} \rightarrow$ the domain is $(-\infty,+\infty)$ $(\frac{f}{g})(x)=\frac{1}{2} \rightarrow$ the domain is $(-\infty,+\infty)$