Question 968908
Start with the factored form.  You are interested in a format {{{(x-m)(x-n)=0}}}.


Your two possible solutions are to be   -5  and  -3.
Using Zero Product Rule,  
{{{(x-(-5))(x-(-3))=0}}}
{{{(x+5)(x+3)=0}}}, a factored form of the quadratic equation you want.  If you want the general form, then just perform the multiplication.