for the first root x=1
[tex]\begin{gathered} x=1 \\ (x-1) \end{gathered}[/tex]for the second root x=-7i
[tex]\begin{gathered} x=-7i \\ x^2=-49 \\ (x^2+49) \end{gathered}[/tex]to find the polynomial in standard form we multiply both expressions:
[tex](x-1)\cdot(x^2+49)[/tex][tex]x^3-x^2+49x-49[/tex]