1) 4A - A^3 = A*(4 - A^2) = A*( 2 - A)*( 2 + A ) ================================= 2) AX^2 + 2AX + A = A * ( X^2 + 2X + 1 ) -- -- -- -- X^2 + 2X + 1 = ( X + 1 )*( X + 1 ) D = 4 - 4*1*1 = 0 X = ( - 2 ) : 2 = ( - 1 ) -- -- --- AX^2 + 2AX + A = A * ( X + 1 )*( X + 1 )