X^2 - 3x - 10 = ( x - 5 )( x + 2 )D = 9 + 40 = 49 = 7^2 x1 = ( 3 + 7 ) : 2 = 5 x2 = ( 3 - 7 ) : 2 = - 2 ----------------------------------------------Выражениe в скобке :общий множитель ( x + 2 )( x - 5 ) x ≠ - 2 ; x ≠ 5 ( x( x - 5 ) + 4 - 2( x + 2 )) / ( ( x + 2 )( x - 5 )) = ( x^2 - 5x + 4 - 2x - 4 ) / ( ( x - 5 )( x + 2 )) = ( x^2 - 7x ) / ( ( x - 5 )( x + 2 )) = ( x( x - 7 )) / ( ( x - 5 )( x + 2 )) --------------------------------------------------x^2 + 2x = x( x + 2 ) ( x( x - 7 ))/((x - 5)( x + 2 )) : (( x - 7 )/( x( x + 2 )) = x^2 / ( x - 5 )