Answer
$x^{2}+4x+3=0$
Work Step by Step
$x=-1$ or $ x=-3\qquad$....get $0$'s on one side.
$x+1=0$ or $ x+3=0\qquad$....Use the principle of zero products (multiplying). The solutions of this equation are $-1$ and $-3$.
$(x+1)(x+3)=0\qquad$...use the FOIL method to multiply.
$ x^{2}+3x+x+3=0\qquad$...combine like terms.
$x^{2}+4x+3=0$