a=√2+1,b=√3-1
a²+ab-b²=(√2+1)²+(√2+1)(√3-1)-(√3-1)²
=3+2√2+√6-√2+√3-1-(3-2√3+1)
=-2+√6+√2+3√3.
你可能打错题目了.没打错