Expression 3: "I" Subscript, 3 , Baseline left parenthesis, "x" , right parenthesis equals "e" Superscript, negative StartAbsoluteValue, "x" , EndAbsoluteValue Superscript, "x" , Baseline "n" pi sin left parenthesis, "n" pi "x" , right parenthesis , Baseline times StartAbsoluteValue, "x" , EndAbsoluteValue Superscript, left parenthesis, StartAbsoluteValue, "x" , EndAbsoluteValue Superscript, "x" , Baseline cos left parenthesis, "n" pi "x" , right parenthesis , right parenthesis , Baseline times sine left parenthesis, StartAbsoluteValue, "x" , EndAbsoluteValue Superscript, "x" , Baseline "n" pi cos left parenthesis, "n" pi "x" , right parenthesis plus 1 half StartAbsoluteValue, "x" , EndAbsoluteValue Superscript, "x" , Baseline ln left parenthesis, "x" squared , right parenthesis sin left parenthesis, "n" pi "x" , right parenthesis , right parenthesis left brace, "x" less than or equal to 0 , right braceI3x=e−xxnπsinnπx·xxxcosnπx·sinxxnπcosnπx+12xxlnx2sinnπxx≤0