( x - 1 ) ( x +3 ) = x² - x + 3 x - 3 = x² + 2 x - 3
( x + 1 ) ( x - 4 ) = x² + x - 4 x - 4 = x² - 3 x - 4
( x - 1 ) ( x + 5 ) = x² - x + 5 x - 5 = x² + 4 x - 5
( 2 x + 3 ) ( x + 4 ) = 2 x² + 8 x + 3 x + 12 = 2 x² + 11 x + 12
( 3 x - 5 ) ( x + 2 ) = 3 x² + 6 x - 5 x - 10 = 3 x² + x - 10
( x - 5 ) ( 7 x - 4 ) = 7 x² - 4 x - 35 x + 20 = 7 x² - 39 x + 20
