Doubt from functions

#1

Example 1.67 how at last moment it becomes less than or equal to zero when it was greater than or equal to zero

#2

If you have done quadratic equation you would know.
As equation is always greater than equal to zero..... Its discriminant will either 0 or less than zero as parabola either touches the axis at one point or at neither

#3

#4

I hope you understand :slight_smile:

#5