\[(x + y - 1)\left( y^{2} + 6y + 9 \right) = 0\]
\[x + y - 1 = 0\]
\[x = 1 - y.\]
\[y^{2} + 6y + 9 = 0\]
\[(y + 3)^{2} = 0\]
\[y = - 3.\]
\[x = 1 - ( - 3) = 4.\]