Bài `33:`

`đk: x > 0, y > 0`

`N = ((sqrt{x}-sqrt{y})^2 + 4sqrt{xy})/(sqrt{x}+sqrt{y}) - (xsqrt{y} - ysqrt{x})/(sqrt{xy})`

`to N = (x - 2sqrt{xy} + y + 4sqrt{xy})/(sqrt{x}+sqrt{y}) - (sqrt{xy}(sqrt{x}-sqrt{y}))/(sqrt{xy})`

`to N = (x + 2sqrt{xy} + y)/(sqrt{x}+sqrt{y}) - (sqrt{x}-sqrt{y})`

`to N = (sqrt{x}+sqrt{y})^2/(sqrt{x}+sqrt{y}) - (sqrt{x}-sqrt{y})`

`to N = (sqrt{x}+sqrt{y}) - (sqrt{x}-sqrt{y})`

`to N = 2sqrt{y}`

`N = 2sqrt{2005}`

`to 2sqrt{y} = 2sqrt{2005}`

`to sqrt{y} = sqrt{2005}`

`to y = 2005 (tmđk)`

Bài `34:`

`đk: a >= 0, a ne 1`

`N = (1 + (a+sqrt{a})/(sqrt{a}+1)) * (1 - (a-sqrt{a})/(sqrt{a}-1))`

`to N = (1 + (sqrt{a}(sqrt{a}+1))/(sqrt{a}+1)) * (1 - (sqrt{a}(sqrt{a}-1))/(sqrt{a}-1))`

`to N = (1 + sqrt{a}) * (1 - sqrt{a})`

`to N = 1 - a`

`N = -2004`

`to 1 - a = -2004`

`to a = 1 + 2004`

`to a = 2005 (tmđk)`