(3x^2-2x-1) - (5x^2+4x+2)

( 3 x ^ 2 - 2 x - 1 ) - ( 5 x ^ 2 + 4 + 2 ) =

3 x ^ 2 - 2 x - 1 - 5 x ^ 2 - 4 x - 2 =

- 2 x ^ 2 - 6 x - 3