求20道二次根式习题及20道一元二次方程，都要带答案，尽量简单的。

Answer 1

①5√8-2√32 √50 =5*3√2-2*4√2 5√2 =√2(15-8 5) =12√2 ②√6-√3/2-√2/3 =√6-√6/2-√6/3 =√6/6 ③(√45 √27)-(√4/3 √125) =(3√5 3√3)-(2√3/3 5√5) =-2√5 7√5/3 ④(√4a-√50b)-2(√b/2 √9a) =(2√a-5√2b)-2(√2b/2 3√a) =-4√a-6√2b ⑤√4x*(√3x/2-√x/6) =2√x(√6x/2-√6x/6) =2√x*(√6x/3) =2/3*|x|*√6 ⑥(x√y-y√x)÷√xy =x√y÷√xy-y√x÷√xy =√x-√y ⑦(3√7 2√3)(2√3-3√7) =(2√3)^2-(3√7)^2 =12-63 =-51 ⑧(√32-3√3)(4√2 √27) =(4√2-3√3)(4√2 3√3) =(4√2)^2-(3√3)^2 =32-27 =5 ⑨(3√6-√4) =(3√6)^2-2*3√6*√4 (√4)^2 =54-12√6 4 =58-12√6 ⑩（1 √2-√3）（1-√2 √3） =[1 (√2-√3)][1-(√2-√3)] =1-(√2-√3)^2 =1-(2 3 2√6) =-4-2√6