( 5х - 3 )( 2х + 1 ) - ( 2х - 3 )( 5х + 4 ) = -3
(10x² - 6x + 5x - 3) - (10x² - 15x + 8x - 12) = -3
6x + 9 = -3
3(2x + 3) = -3
6х + 9 = -3
( 6х : 3х) + ( 9 : 3 ) = -3 : 3
2х + 3 = -1
2х = -1 - 3
2х = -4
х = -4 : 2
х = -2
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( 5 × (-2) - 3 )( 2 × (-2) + 1 ) - ( 2 × (-2) - 3 )( 5 × (-2) + 4 ) = -3