Question 81520
The following shows the graph for y = x^2 - 12x + 36

{{{ graph( 300, 200, -10, 10, -10, 20, x^2-12x+36) }}}

The solution to the equation x^2 - 12x + 36 = 0 are the points where the graph cuts the x axis.

In the above fig, we find that the graph touches the x axis at only one point namely 6.

Thus x = 6 is the only solution for the given graph.