$${\mathtt{u1}} = {\frac{\left({\mathtt{18}}{\mathtt{\,\times\,}}{\mathtt{a}}{\mathtt{\,-\,}}{\sqrt{{\mathtt{252}}{\mathtt{\,\times\,}}{{\mathtt{a}}}^{{\mathtt{2}}}}}\right)}{\left({\mathtt{18}}{\mathtt{\,\times\,}}{{\mathtt{a}}}^{{\mathtt{2}}}\right)}}$$
$${\mathtt{u1}} = {\frac{\left({\mathtt{18}}{\mathtt{\,\times\,}}{\mathtt{a}}{\mathtt{\,-\,}}{\sqrt{{\mathtt{36}}{\mathtt{\,\times\,}}{{\mathtt{a}}}^{{\mathtt{2}}}{\mathtt{\,\times\,}}{\mathtt{7}}}}\right)}{\left({\mathtt{18}}{\mathtt{\,\times\,}}{{\mathtt{a}}}^{{\mathtt{2}}}\right)}}$$
$${\mathtt{u1}} = {\frac{\left[{\mathtt{18}}{\mathtt{\,\times\,}}{\mathtt{a}}{\mathtt{\,-\,}}\left({\mathtt{6}}{\mathtt{\,\times\,}}{\left|{\mathtt{a}}\right|}{\mathtt{\,\times\,}}{\sqrt{{\mathtt{7}}}}\right)\right]}{\left({\mathtt{18}}{\mathtt{\,\times\,}}{{\mathtt{a}}}^{{\mathtt{2}}}\right)}}$$
$${\mathtt{u1}} = {\frac{\left[{\mathtt{3}}{\mathtt{\,\times\,}}{\mathtt{a}}{\mathtt{\,-\,}}\left({\left|{\mathtt{a}}\right|}{\mathtt{\,\times\,}}{\sqrt{{\mathtt{7}}}}\right)\right]}{\left({\mathtt{3}}{\mathtt{\,\times\,}}{{\mathtt{a}}}^{{\mathtt{2}}}\right)}}$$
Ergänzung: (Danke Radix) Ich hätte das abs(a) und a nicht zusammen gefasst...
$${\mathtt{u1}} = {\frac{{\mathtt{a}}{\mathtt{\,\times\,}}\left({\mathtt{3}}{\mathtt{\,-\,}}{\sqrt{{\mathtt{7}}}}\right)}{\left({\mathtt{3}}{\mathtt{\,\times\,}}{{\mathtt{a}}}^{{\mathtt{2}}}\right)}}$$
$${\mathtt{u1}} = {\frac{\left({\mathtt{3}}{\mathtt{\,-\,}}{\sqrt{{\mathtt{7}}}}\right)}{\left({\mathtt{3}}{\mathtt{\,\times\,}}{\mathtt{a}}\right)}}$$
.