11.1 Simplify the expression

$$
\frac{\sqrt{a^{2}-2 a b+b^{2}}}{\sqrt[4]{(b-a)^{3}}}
$$
11.1 The denominator of the fraction makes sense when $b-a>0$. Taking this into account, let's simplify the numerator:

$\sqrt{a^{2}-2 a b+b^{2}}=\sqrt{(a-b)^{2}}=|a-b|=b-a$.

Finally, we get $\frac{b-a}{\sqrt[4]{(b-a)^{3}}}=\sqrt[4]{b-a}$, where $b>a$.