Answer
$\color{blue}{x^2-x}$
Work Step by Step
RECALL:
$(a+b)(a-b)=a^2-b^2$
Use the formula above with $a=x$ and $b=x^{1/2}$ to obtain:
$=x^2-(x^{1/2})^2$
Use the rule $(a^m)^n = a^{mn}$ to obtain:
$=x^2 - x^{(1/2)\cdot 2}
\\=x^2-x^1
\\=\color{blue}{x^2-x}$
