Question 890230
An explanation? ?


Imagine you have {{{y=ax^2+bx+c}}} and you believe or you know that this meets or crosses the x axis.  Assume this equation is factorable as {{{y=a(x+u)(x+v)}}}.  The graph intersects the x axis if for some value of x, y=0.  This makes for the equation {{{a(x+u)(x+v)=0}}}.


Can you figure how to say the rest of this if more is needed?