a) 6a^2-3a+1+6a^2-1=12a^2-3a+1
6a^2-3a+1-(6a^-1)=6a^2-3a+1-6a^2+1=-3a+2
,б) n^3+2n^2-n+1+1-n^3=2n^2-n+2
n^3+2n^2-n+1-(1-n^3)=n^3+2n^2-n+1-1+n^3=2n^3+2n^2-n
в) r^3-3r^2+1 + 2r^3-3r2+4=3r^3-6r^2+5;
r^3-3r^2+1 -( 2r^3-3r2+4)= r^3-3r^2+1 - 2r^3+3r2-4=-r^3-3
г) 3x^2-2x+7 + 2x^2+2x+7=5x^2+14
3x^2-2x+7 -( 2x^2+2x+7)= 3x^2-2x+7 - 2x^2-2x-7=x^2
a) 6a^2-3a+1+6a^2-1=12a^2-3a+1
6a^2-3a+1-(6a^-1)=6a^2-3a+1-6a^2+1=-3a+2
,б) n^3+2n^2-n+1+1-n^3=2n^2-n+2
n^3+2n^2-n+1-(1-n^3)=n^3+2n^2-n+1-1+n^3=2n^3+2n^2-n
в) r^3-3r^2+1 + 2r^3-3r2+4=3r^3-6r^2+5;
r^3-3r^2+1 -( 2r^3-3r2+4)= r^3-3r^2+1 - 2r^3+3r2-4=-r^3-3
г) 3x^2-2x+7 + 2x^2+2x+7=5x^2+14
3x^2-2x+7 -( 2x^2+2x+7)= 3x^2-2x+7 - 2x^2-2x-7=x^2