Answer:
1. There will be two roots not only one
2.a(
+16) =0
Explanation:
Simply assume a quadratic equation

Here a,b,c are real independent variables.
As given by student -4i is one of it's root it must satisfy the equation.
-16a +4ib+c=0
b must be zero otherwise either a or c must be imaginary number which is not possible.
So b =0
then, c= 16a
a
+c=a
+16a
Quadratic is a(
+16) =0 here a is any real number.