根号8减2倍根号0.5的和减去根号9/8加根号50加2/3倍的根号72
=2根号2-2/2*根号2-3/4根号2+5根号2+2/3*3*2根号2
=根号2-3/4根号2+5根号2+4根号2
=10根号2-3/4根号2
=37/4*(根号2)