Answer:
-3 comes from combining 1 and -4
Step-by-step explanation:
The -3 under the radical is the result of combining the terms
16 -4(16) = 16(1 -4) = 16(-3) = -3(16)
16 is factored out. It is done this way because 16 is a perfect square factor, so wants to maintain that identity while you figure out the rest of the radical.
[tex]=\dfrac{-4\pm\sqrt{16-4(16)}}{2}=\dfrac{-4\pm\sqrt{16(1-4)}}{2}=\dfrac{-4\pm\sqrt{-3(16)}}{2}\\\\=\dfrac{-4\pm\sqrt{-3(4^2)}}{2}=\dfrac{-4\pm 4\sqrt{-3}}{2}=-2\pm2\sqrt{-3}=-2\pm2i\sqrt{3}[/tex]
