## Measure of open intervals and half-open half-closed intervals

Solution to Measure, Integration & Real Analysis by Axler Section 2A Exercise 2A6 Prove that if $a,b\in\mathbf R$ and $a<b$, then $$|(a,b)|=|(a,b]|=|[a,b)|=b-a.$$ Solution 1: Since $(a,b)\subset [a,b]$, by 2.5 and…