( f : R rightarrow R , ) যেখানে ( f left( right. x left. right) = x^ 2 - 2 left| right. x left| right. ) এবং ( g : R rightarrow R , ) যেখানে ( g left( right. x left. right) = x^ 2 + 1 ; " left( right. g o f left. right) left( right. - 4 left. right) " ) এর মান কত?