1. The problem statement, all variables and given/known data Find a delta such that |f(x)-l|< epsilon for all x satisfying 0<|x-a|< delta f(x)=(x^4)+(1/x); a=1; l=2 2. Relevant equations Lemma Theorem 3. The attempt at a solution 0<|x-1|<delta; |(x^4)+(1/x)-2|<epsilon |x^4-1|<epsilon/2 and |(1/x)-1|<epsilon/2 Then I applied third item of the Lemma which is if y0 not equal to 0; |y-y0|<min(|y0|/2,(epsilon*|y0|^2)/2) then y not equal to 0 and; |(1/y)-(1/y0)|<epsilon Then I concluded that the |(1/x)-1|<epsilon/2 part of the solution as; |x-1|<min(1/2,epsilon/2) However, I could not find any approach for the |x^4-1|<epsilon/2 Which method shall I apply here? Any helps will be appreciated.