А)
( а^2 + 5а ) / ( 5b + ab ) = ( a( a + 5 )) / ( b( 5 + a )) = a / b
Б)
( 1 - n ) / ( n^2 - n ) = ( 1 - n ) / ( n( n - 1 )) = 1 / ( - n )
B)
( X - y )^2 / ( y^2 - x^2 ) = ( ( X - y )( X - y )) / ( y - X )( y + X )) = ( - ( X - y )) / ( y + X ) = ( y - X ) / ( y + X )
Г)
1) 3а^2 + 7а - 6 = 3( a - ( 2/3 ))•( a + 3 ) = ( 3a - 2 )•( a + 3 )
D = 49 + 72 = 121 = 11^2
a1 = ( - 7 + 11 ) : 6 = 2/3
a2 = ( - 7 - 11 ) : 6 = - 3
2) ( ( 3a - 2 )( a + 3 )) / ( a( 3a - 2 )) = ( a + 3 ) / a