Answer:
The domain is [tex]x\in (-\infty,\infty).[/tex]
Step-by-step explanation:
Given functions [tex]f(x)=x^2+3x+1[/tex] and [tex]g(x)=2x^2-4x-1[/tex]
Subtract these two functions:
[tex]f(x)-g(x)\\ \\=(x^2+3x+1)-(2x^2-4x-1)\\ \\=x^2+3x+1-2x^2+4x+1\\ \\=(x^2-2x^2)+(3x+4x)+(1+1)\\ \\=-x^2+7x+2[/tex]
Plot these difference on the coordinate plane (see attached diagram). This function is defined for all vlues of x, so the domain is [tex]x\in (-\infty,\infty).[/tex]