If the second derivative of a function is zero, then the function has a constant slope, and that function is linear. Therefore, any point that belongs to that function lies on a line.
The roots of a quadratic function are where the lies interescts with the x-axis. There can be as little as zero.
(6,5)
The point lies 1 unit below the regression line.
A function is positive on an interval, say, the interval from x=a to x=b, if algebraically, all the y-coordinate values are positive on this interval; and graphically, the entire curve or line lies above the x-axis.on this interval.