Răspuns :
2(x²+2x+1) -3(x²-4)+5x²-15x -(9x²+6x+1)=
=2x² +4x +2 -3x²+12 +5x² -15x -9x² -6x-1=
=7x² -9x² +4x -21x+14 -1=
=2x²-17x+13
=2x² +4x +2 -3x²+12 +5x² -15x -9x² -6x-1=
=7x² -9x² +4x -21x+14 -1=
=2x²-17x+13
2(x²+2x+1) -3(x²-4)+5x²-15x -(9x²+6x+1)=2x² +4x +2 -3x²+12 +5x² -15x -9x² -6x-1=7x² -9x² +4x -21x+14 -1=2x²-17x+13