x^(1/2)+x^(-1/2)=3两边平方：x+1/x+2=9即x+1/x=7两边平方：x²+1/x²+2=49所以x²+1/x²=47即x²+x-²=47x^(3/2)+x^(-3/2)=[x^(1/2)+x^(-1/2)]*[x-1+1/x]=3*(7-1)=18所以，[x^(3/2)+x^(-3/2)]/(x²+x-²)=18/47
