(a+1/a)^2=a^2+2+1/a^2=1/12+2+12=14 1/12=169/12
((a+1)^2-2a)^2=(a^2+1)^2=(1/12+1)^2=(13/12)^2=169/144
169/12:(169/144)=12
(a+1/a)^2=a^2+2+1/a^2=1/12+2+12=14 1/12=169/12
((a+1)^2-2a)^2=(a^2+1)^2=(1/12+1)^2=(13/12)^2=169/144
169/12:(169/144)=12