use 5.020;
use Encode;
sub show {
    my ($char) = @_;
    printf "%s = %vx\n",encode('UTF-8',$char),$_[0];
}

my $emu = "\xc2\xb5";
show $emu;                      # µ = c2.b5

my $mu = decode('UTF-8',$emu);
show $mu;                       # µ = b5

$emu =~ s/(\x{B5}|\x{BC})/u/g; # Don't do this!
show $emu;                     # Âu = c2.75

$mu =~ s/(\x{B5}|\x{BC})/u/g;  # That's how to do it
show $mu;                      # u = 75