4道化简题@!3分之根号42+根号5分之9-根号20分之8（8不是根号）2√2/3 -√1/6 +1/6√54√18-√

(42^0.5)/3+(9/5)^0.5-8/(20^0.5)
=(42^0.5)/3+3/(5^0.5)-8/(2*5^0.5)
=(42^0.5)/3+3/(5^0.5)-4/(5^0.5)
=(42^0.5)/3+(3-4)/(5^0.5)
=(42^0.5)/3-(5^0.5)
=(42^0.5-3*5^0.5)/3
2√(2/3)-√(1/6)+1/(6√54)
=(2√2)/√3-(1/√6)+1/(6√54)
=(2*2)/√6-(1/√6)+1/(6√54)
=(3/√6)+1/(6√(6*9)
=(3/√6)+1/(18√6)
=(54+1)/(18√6)
=55/(18√6)
√18-√12/(3√2)+2√3
=3√2-(2√3)/(3√2)+2√3
=3√2-(√2/√3)+2√3
=(3√6-√2+2*3)/√3
=(3√6-√2+6)/√3
=(3*3√2-√2*√3+6√3)/3
=(9√2+(6-√2)*√3)/3
√32+√12+√8/(√32)-√12-√8
=2√8+√8/(2√8)-√8
=√8+1/2
=2√2+1/2
=(4√2+1)/2