Answer:

12

Step-by-step explanation:

[tex]( {a - b})^{3} = {a}^{3} - {b}^{3} - 3ab(a - b)[/tex]

[tex](x - 1 \div x) = {x}^{3} - {1 \div x}^{3} - 3(x - 1 \div x)[/tex]

36-3(x-1/x)=0

X-1/x= 12