Answer:
complex solutions: x = -7 ± i√2
Step-by-step explanation:
[tex]-2x^2-28x-102=0\\{}\qquad\qquad^{\div(-2)}\qquad\ \ ^{\div(-2)}\\x^2+14+51=0\quad\implies\quad a=1\,,\ b=14\,,\ c=51\\\\\\x=\dfrac{-b\pm\sqrt{b^2-4ac}}{2a}=\dfrac{-14\pm\sqrt{14^2-4\cdot1\cdot51}}{2\cdot1}=\dfrac{-14\pm\sqrt{196-204}}{2}[/tex]
[tex]x=\dfrac{-14\pm\sqrt{-8}}{2}[/tex] means NO REAL SOLUTIONS (as there is no real √[-8])
However in complex numbers we have:[tex]x=\dfrac{-14\pm\sqrt{-8}}{2}=\dfrac{-14\pm2\sqrt{-2}}{2}=\dfrac{2(-7\pm\sqrt{-2})}{2}=-7\pm\sqrt{-2}\\\\\\x_1=-7+i\sqrt2\ ,\qquad x_2=-7-i\sqrt2[/tex]
