Освобадить заминятел от ирацалности

[latex]\frac{6}{1- \sqrt{7}}= \frac{6}{1- \sqrt{7}}* \frac{1+\sqrt{7}}{1+\sqrt{7}}= \frac{6(1+\sqrt{7})}{(1- \sqrt{7})*(1- \sqrt{7})}=\frac{6(1+\sqrt{7})}{(1^-( \sqrt{7})^2}=\frac{6(1+\sqrt{7})}{(1^-( \sqrt{7})^2}= \\ =\frac{6(1+\sqrt{7})}{1-7}=\frac{6(1+\sqrt{7})}{-6}=-(1+ \sqrt{7})=-1- \sqrt{7} [/latex]