(a- 1/a)^2=(a+ 1/a)^2-4=5
∵a & gt; 1
∴a- 1/a= radical number 5.
☆☆☆☆ ☆☆☆☆
★★ ★ ★★
☆☆ I wish you happiness! ☆☆
★★ ★★
☆☆ ☆☆
☆☆
Dear, * _ *, I don't know, please accept it if you are satisfied, thank you!