Question 156833
y=x-3 (red line)
y=x^2-5x+6 (green curve) 
{{{ graph( 300, 200, -6, 5, -10, 10, x -3, x^2 -5x +6) }}} (graph 300x200 pixels, x from -6 to 5, y from -10 to 10, of TWO functions x -3 and x^2 -5x +6). 
A picture is worth many calculations.