Draw the graph of y=x2−4x+6 and show that it does not have real roots.
To draw the graph, consider the following table
x01−12y631112
Scale: x-axis 1 cm = 2 units; y-axis 1 cm = 2 units
The graph lies above the x- axis. Since it is not intersecting the x- axis, the roots of the graph are not real.