Разложите на множители квадратный трехчлен,

1)

  x² - 3x + 2 =

= x² - x - 2x + 2 =

= (x² - x) - (2x - 2) =

= x·(x - 1) - 2·(x - 1) =

= (x - 1)·(x - 2)  

2)

 2x² + 3x + 1 =

= 2x² + 2x + x + 1 =

= (2x² + 2x) + (x + 1) =

= 2x·(x + 1) + 1·(x + 1) =

= (x + 1)·(2x + 1)  

3)

  2x² + 7x - 4 =

= 2x² + 8x - x - 4 =

= (2x² + 8x) - (x + 4) =

= 2x·(x + 4) - 1·(x + 4) =

= (x + 4)·(2x - 1)