Question 937671
{{{ ((c^2+1)(c-1)^2)/(c^4-1) = ((c^2+1)(c-1)(c-1))/((c^2+1)(c^2-1)) =((c^2+1)(c-1)(c-1))/((c^2+1)(c-1)(c+1))=(c-1)/(c+1)}}}