1) (2n²-3n+2n-3)+(3n²+n-3n-1)=5n²-3n-4
2) (2x²-3xy-2xy+3y²)-(6x²+3xy-2xy-y²) =4y²-4x²-6xy=2(2y²-2x²-3xy)
3) (4a²+6a+6a+9)-(4a²-2a+2a-1)=12a+10=2(6a+5)
4) (3cd+9c²-d²-3cd)+(4c²-16cd-cd+4d²) =13c²-17cd+d²
1) (2n²-3n+2n-3)+(3n²+n-3n-1)=5n²-3n-4
2) (2x²-3xy-2xy+3y²)-(6x²+3xy-2xy-y²) =4y²-4x²-6xy=2(2y²-2x²-3xy)
3) (4a²+6a+6a+9)-(4a²-2a+2a-1)=12a+10=2(6a+5)
4) (3cd+9c²-d²-3cd)+(4c²-16cd-cd+4d²) =13c²-17cd+d²