1.2√2-4√1/27+3√48=2√2-4√3/9+12√3=2√2+104√3/9
2.(√3-√2)(-√3-√2)=(-√2)²-(√3)²=2-3=-1
3.已知a=2+√5,b=2-√5,
√a^2-ab+b^2=√(9+4√5)-(4-5)+(9-4√5)=√19求补充问题答案由题意知m是负数-√-m^3-m√-1/m=-（-m)√-m-m*(-1/m)√-m=m√-m+√-m=(m+1)√-m