where a, b, and c are constants.
The roots of this equation are the points at which y=0. That is, the roots are where the graph of Eq.(1)
crosses the xaxis.
In the case that a is zero, Eq.(1) is that of the straight line y = bx + c. Then there is only a
single root, or point where the line crosses the xaxis. That point is at (x, y) is (c/b, 0).
We are interested in the nontrivial case where a is nonzero. The roots of our quadratic are the solutions
to
