Answer :
[tex]f(x)=-5x-1;\ D_f:x\in\mathbb{R}\\\\g(x)=2x^2;\ D_g:x\in\mathbb{R}\\\\D_f=D_g\ then\ (f+g)(x)=f(x)+g(x)\\\\(f+g)(x)=-5x-1+2x^2=2x^2-5x-1[/tex]
[tex] \{f + g \}(x) = (-5x - 1 )\ +\ 2 x^{2} \\\\= 2 x^{2} -5x - 1\ \ Answer[/tex]
