Răspuns :
[tex] x^{2} +6x+9+1= (x+3)^{2} +1 \\ (X+3)^{2} \geq 0|+1 \\ (x+3)^{2} +1 \geq 1\ \textgreater \ 0[/tex]
[tex] x^{2} -8x+16+4= (x-4)^{2} +4 \geq 0+4 \geq 4\ \textgreater \ 0[/tex]
[tex] x^{2} -8x+16+4= (x-4)^{2} +4 \geq 0+4 \geq 4\ \textgreater \ 0[/tex]