Question 279665
If you say the roots are {{{r[1]}}} and {{{r[2]}}}
{{{(x - r[1])*(x - r[2]) = 0}}}
{{{x^2 - (r[1] + r[2])*x + r[1]*r[2] = 0}}}
and, since
{{{ax^2 + bx + c = 0}}}
{{{x^2 + (b/a)*x + c/a = x^2 + (r[1] + r[2])*x + r[1]*r[2]}}}
so
{{{c/a = r[1]*r[2]}}}