已知x^1/2+x^-1/2+3,求x+x^-1的值有错,已知x^1/2+x^-1/2=3,求x+x^-1的值

已知x^1/2+x^-1/2+3,求x+x^-1的值有错,已知x^1/2+x^-1/2=3,求x+x^-1的值
已知x^1/2+x^-1/2+3,求x+x^-1的值
有错,已知x^1/2+x^-1/2=3,求x+x^-1的值

已知x^1/2+x^-1/2+3,求x+x^-1的值有错,已知x^1/2+x^-1/2=3,求x+x^-1的值
已知x^1/2+x^-1/2=3,
则两边同时平方得
x+x^(-1)+2=9
x+x^-1=7