Question

$( frac{1}{x^{1/2} } - x^{1/2} )( frac {x^{1/2}+1 }{x^{1/2}-1 } - frac {x^{1/2}-1 }{x^{1/2}+1 } )$

Answer 1

x^ 1/2 = a 
1) ( a + 1 ) / ( a - 1 ) - ( a - 1 ) / ( a + 1 ) = ( ( a + 1 )² - ( a - 1 )² )/( a² - 1 ) =
= ( a² + 2a + 1 - ( a² - 2a + 1 )) / ( a² - 1 ) = ( a² + 2a + 1 - a² + 2a - 1 )/(a² - 1 ) =
= 4a / ( a² - 1 ) 
2) 1 / ( a ) - a = ( 1 - a² ) / a 
3) ( 4a/( a² - 1 ))*( ( 1 - a² )/a ) = - 4 
Ответ ( - 4 )