[tex] x^2+ 16x + 63=0 \\ \\a=1, \ b=16 , \ c=63 \\ \\ \Delta =b^2-4ac =16^2 -4\cdot1\cdot 63 = 256 -252 = 4 \\ \\x_{1}=\frac{-b-\Delta }{2a}=\frac{-16-\sqrt{4}}{2 }=\frac{-16-2}{2}=-\frac{-18}{2}=-9 \\ \\x_{2}=\frac{-b+\Delta }{2a}=\frac{-16+\sqrt{4}}{2 }=\frac{-16+2}{2}=-\frac{-14}{2}=-7 \\ \\ \\Answer : \ x= -7 \ \ or \ \ x= -9[/tex]
