(1)1/5根号900+1/2根号121
=(1/5)*30 + (1/2)*11
=6+ 5.5
=11.5
(2)根号12+根号1/27-根号1/3(3)根号1/7+根号28-根号700
=2根号3 + (根号3)/9 - (根号3)/3
=(2 + 1/9 - 1/3)*根号3
=16(根号3)/9
（4）根号32-3根号1/2+根号8
=4根号2 - 3(根号2)/2 + 2根号2
=9(根号2)/2