X加X分之一等于3,问X的二分之三次幂加上X的负二分之三次幂的值,即x+1/x=3,问x3/2+x-3/2=多少

x+1/x=3[x^(1/2)+x^(-1/2)]^2 -2=3x^(1/2)+x^(-1/2)=±√5x^(1/2)和x^(-1/2)要有意义,那么x>0,x^(1/2)>0,x^(-1/2)>0所以x^(1/2)+x^(-1/2)=√5x^(3/2)+x^(-3/2)=[x^(1/2)+x^(-1/2)](x+1/x-1)=√5*(3-1)=2√5...