2x- 1 & gt； = 0x & gt； =0.5

1-2x & gt； = 0x & lt； =0.5

So x=0.5 and y= 1/3.

So 1/x+ 1/y=2+3=5.

2.

Let the original formula = k > 0.

k^2=y/x+x/y+2

=(x^2+y^2)/xy+2

=[(x+y)^2-2xy]/xy+2

=[5^2-2*3]/3+2

= 5/3 times the root number 3.

3.

x^2- 1<； 5 x^2<； Root 5

(x^2- 1)^2- 1>； 5 x^2- 1>； Root 6

Vertical x 2 = 4 x = 2 or -2

The result is (2 times root 2)- (root 6)