Question 1124820
{{{(x-(-3))(x-4)=Ax^2+Bx+C}}}

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{{{(x+3)(x-4)=Ax^2+Bx+C}}}

{{{x^2+3x-4x-12}}}

{{{x^2-x-12=Ax^2+Bx+C}}}


Equating the corresponding terms, one possible set of values is
{{{system(A=1,B=-1,C=-12)}}}



Any positive real value k will also make {{{k(x^2-x-12)=Ax^2+Bx+C}}} and with this, other more general possible values may be  {{{system(A=k,B=-k,C=-12k)}}} for real {{{k>0}}}.