Answer
$x^{2} -2x-3$
Work Step by Step
$(x+1)(x-3)$
1. Multiply the terms that occur first in each bracket. $(x)(x) = x^{2}$
2. Multiply the outermost terms in each bracket. $(x)(-3) = -3x$
3. Multiply the innermost terms in each bracket. $(1)(x) = x$
4. Multiply the last terms in each bracket. $(1)(-3) = -3$
5. Add all the answers in steps 1-4 to get $x^{2} -3x+x-3$.
6. Simplify to get $x^{2} -2x-3$.