polynomial error on sparknotes?

<p>hence this website; [SparkNotes:</a> SAT Subject Test: Math Level 1: Polynomials](<a href=“SparkNotes: Today's Most Popular Study Guides”>SparkNotes: Today's Most Popular Study Guides)</p>

<p>Doesn’t the polynomial (X+1) * (X+3) equals to the answer below instead of the listed answer on the webpage? If not, what am i doing wrong?..</p>

<p>= Xsquard + 3x+x+3
= [xsquared + 4x + 3]</p>

<p>It’s a mistake…</p>