Multiplying polynomials / distributive property of an exponent I am doing an Algebra course (UC Irvine / Coursera), and am having a bit of trouble understanding the following property:
$$
3(x+h)^2
$$
Seems to be distributed as such:
$$
3(x^2+2xh+h^2)
$$ 
.. now, due to the distributive property, I understand why the $x^2$ and $h^2$ are so, but I have no idea where the "extra" $2xh$ came from. I've been grappling with the fact that while the original quantity can be represented as,
$$
3(x+h)(x+h)
$$
..it's just not clear to me how the $2xh$ is "created".
Any advice on this would be appreciated.
NB: This is not an assignment; it's from Week 2, Lecutre "Multiple Operations with Polynomials", at about 5:30.
Thanks!
sc.

$(x+h)(x+h)=x(x+h)+h(x+h)=\\
=x\cdot x+x\cdot h+h\cdot x+h\cdot h=\\
=x^2+xh+hx+h^2=\\
=x^2+2xh+h^2$
$2xh$ is created from $xh$ and $hx$.
