Answer
See below.
Work Step by Step
Step 1. $tan(\alpha-\beta)=\frac{tan(\alpha)-tan(\beta)}{1+tan(\alpha)tan(\beta)}=\frac{x+1-x+1}{1+(x+1)(x-1)}=\frac{2}{x^2}$
Step 2. $cot(\alpha-\beta)=\frac{1}{tan(\alpha-\beta)}=\frac{x^2}{2}$
Step 3. $2cot(\alpha-\beta)=x^2$
