3. Find the quadratic irrational with simple continued fraction expansion
a) $[2 ; 1, \overline{5}]$
b) $[2 ; \overline{1,5}]$
c) $[\overline{2 ; 1,5}]$.
3. a) $(23 \pm \sqrt{29}) / 10$
b) $(-1+\sqrt{45}) / 2$
c) $(8+\sqrt{82}) / 6$