1) 2y / x - x / 2y = ( 4y^2 - x^2 ) / 2xy = [ ( 2y - x )*( 2y + x ) ] / 2xy ;
2) [ ( 2y - x )*( 2y + x ) ] / 2xy : ( 2y + x ) =
( 2y - x ) / 2xy ;
3) при x = 1/9 ; y = 1/2
( 2 * ( 1/2 )) - 1/9 ) / ( 2 * 1/9 * 1/2 ) = ( 1 -1/9 ) / ( 1/9 ) = ( 8/9 ) / ( 1/9 ) = 8 ; ОТВЕТ 8