Odpowiedź :
b) ( 3x - 2)( 3x - 2y + 1) - 4x ( 2x - 3y + 1) =
=9x²-6xy +3x - 6x+4y -2 - 8x² +12xy - 4x =
x² +6xy-7x +4y - 2
c) 2 ( m + 1) ( n - 2) + 2 ( n +1) ( m - 2) =
=2(mn - 2m + n - 2) + 2( mn - 2n + m - 2)
=2mn -4m +2n -4 + 2mn -4n +2m -4 =
=4mn- 2m- 2n - 8
d) x ( x + 1) ( x + 2) - x ( x -1) ( x - 2)=
= x(x²+2) - x(x²+2) =
x³+ 2x -x³ - 2x = 0
=9x²-6xy +3x - 6x+4y -2 - 8x² +12xy - 4x =
x² +6xy-7x +4y - 2
c) 2 ( m + 1) ( n - 2) + 2 ( n +1) ( m - 2) =
=2(mn - 2m + n - 2) + 2( mn - 2n + m - 2)
=2mn -4m +2n -4 + 2mn -4n +2m -4 =
=4mn- 2m- 2n - 8
d) x ( x + 1) ( x + 2) - x ( x -1) ( x - 2)=
= x(x²+2) - x(x²+2) =
x³+ 2x -x³ - 2x = 0