设X的1/2次方+X的-1/2次方=a则a^2=x+2+1/x因为,X+X的-1次方等于3所以,a^2=3+2=5a=√5即,X的1/2次方+X的-1/2次方=√52、化简得M={Y|Y<=3},N=[x|x>=-1]所以, M∩N=[-1,3]