Answer:
17
Step-by-step explanation:
4×10-9= 4
8×10-7=21
21-4=17
Discriminant of a Quadratic
The number D = b2 – 4ac determined from the coefficients of the equation ax2 + bx + c = 0. The discriminant reveals what type of roots the equation has.
Note: b2 – 4ac comes from the quadratic formula.