根二-1分之1+跟三（跟三-根十二）+根八

1/2(√3-1)²+1/(√2-1)+√3-(√2/2)^-1
=1/2(4-2√3)+√2+1+√3-√2
=2-√3+1+√3
=3

1.
（√8-2√0.25）-[√（9/8）+√50+2√72/3)]
=2√2-1-3√2/4-5√2-4√2
=-1-31√2/4
2.
(20√54-8√24+2√6)÷（-2√6)
=-（60√6-16√6+2√6）/2√6
=-23
3.
（√48-√24+√12）÷√3
=（4√3-2√6+2√3）÷√3
=4-2√2+2
=6-2√2