1. The problem statement, all variables and given/known data Given: |x-a|<ε |y-b|<ε. proove: |xy-ab|<ε(|a|+|b|+ε) 2. Relevant equations I need a direction for this proof. 3. The attempt at a solution I tried by the info: -ε+a<x<ε+a and -ε+b<y<ε+b to ,multiply these inequalities, but it's not true. and i tried with the opposite triangle inequality and it didn't worked.