Let the product be given by the function p(x) where the smallest number is x.

p(x) = x(x+12) = x

P(x) defines a parabola, which will have a minimum at x=-12/2 = -6

The two numbers are -6 and +6.

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The minimum of the expression

ax

is at the value of x given by

x = -b/(2a)

p(x) = x(x+12) = x

^{2}+ 12xP(x) defines a parabola, which will have a minimum at x=-12/2 = -6

The two numbers are -6 and +6.

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The minimum of the expression

ax

^{2}+ bx + cis at the value of x given by

x = -b/(2a)