Sagot :
[tex]f(x)=-6x-1;\ D_f:x\in\mathbb{R}\\\\g(x)=4x^2:\ D_g:x\in\mathbb{R}\\\\D_f=D_g\ then\ (f+g)(x)=f(x)+g(x):\\\\(f+g)(x)=(-6x-1)+(4x^2)=4x^2-6x-1[/tex]
[tex]f(x)=-6x-1\\ g(x)=4x^2 \\\\ (f+g)(x)=f(x)+g(x)\\\\(f+g)(x)=-6x-1+4x^2=4x^2-6x-1[/tex]