Respuesta :

[tex]\begin{gathered} f(x)=x^2+x-1 \\ To\text{ find f(x+1) , we substitute x+1 for x,} \\ f(x+1)=(x+1)^2+x+1-1 \\ =x^2+2x+1+x+1-1 \\ f(x+1)=x^2+3x+1 \end{gathered}[/tex]