2x² - 5x - 3 = 2( x + 0,5 )( x - 3 ) = ( 2x + 1 )( x - 3 )
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D = ( - 5 )² - 4 * 2 * ( - 3 ) = 25 + 24 = 49 = 7²
x1 = ( 5 + 7 ) : ( 2 * 2 ) = 12 : 4 = 3
x2 = ( 5 - 7 ) : ( 2 * 2 ) = - 2 : 4 = - 0,5