Overview
I know the answer but the professor need to show all working and explain please
In the xy-plane, the graph of the function f(x) = x2 + bx + 4 does not intersect the x-axis. Which of the following must be true about b?
A. -8 ≤ b < -4
B. b = -4
C. -4 < b < 4
D. b = 4
E. 4 < b ≤ 8