Question

If a=2+√3 find the value of a- ¹/a
Find the value of x
If (6/5)x (5/6)²n

Answer 1

a=2+✓3
1/a=1/2+✓3
After rationalising,1/a=2-✓3
Now
a-1/a=2+✓3-(2-✓3)
=2+✓3-2+✓3
=2✓3

Answer 2

a=2+✓3
1/a=1/2+✓3
After rationalising,1/a=2-✓3
Now 
a-1/a=2+✓3-(2-✓3)
=2+✓3-2+✓3
=2✓3