1) - 3b^2 + 2b + 16 = - 3*( b + 2 )*( b - 2 2/3 )
D = 4 + 192 = 196 = 14^2
b1 = ( - 2 + 14 ) : ( - 6 ) = - 2
b2 = ( - 2 - 14 ) :( - 6 ) = 8/3 = 2 2/3
2) b^2 + 4b + 4 = ( b + 2 )^2
3) ( - 3( b + 2 )( b - 2 2/3 )) / ( ( b + 2 )^2 ) = ( - 3( b - 2 2/3 )) /( b + 2 ) =
= ( - 3b + 8 ) / ( b + 2 )