1) ( 1 + a )/ ( 9 - a² ) = ( 1 + a ) / ( ( 3 - a )( 3 + a ))
2) ( a + 2 ) / ( a² + 3a ) = ( a + 2 ) / ( a( a + 3 ))
Общий знаменатель а( 3 - a )( 3 + a ) =a( 9 - a² )
( a( 1 + a ) + ( a + 2)( 3 - a )) / ( a( 9 - a² )) = ( a + a² + 3a - a² + 6 - 2a )/ ( a( 9 - a² )) = ( 6 + 2a )/ ( a( 9 - a² )) = ( 2( a + 3 )) / ( a( 3 - a )( 3 + a )) = 2 / (a( 3 - a ) = 2 / ( 3a - a² )
Ответ 2 /( 3a - a² )