\[x(x - 7) + (x + 3)^{2} =\]
\[= x^{2} - 7x + x^{2} + 2 \cdot x \cdot 3 + 3^{2} =\]
\[= x^{2} - 7x + x^{2} + 6x + 9 =\]
\[= 2x^{2} - x + 9.\]