A (a+2) (a-2) - (a-3) (a²+3a+9) = a (a²-4) - (a³-27) = a³-4a-a³+27=27-4a;
a(a-2)(a+2)-(a-3)(a²+3a+9)= a(a²-4)-(a³-27)=a³-4a-a³+27=-4a+27
A (a+2) (a-2) - (a-3) (a²+3a+9) = a (a²-4) - (a³-27) = a³-4a-a³+27=27-4a;
a(a-2)(a+2)-(a-3)(a²+3a+9)= a(a²-4)-(a³-27)=a³-4a-a³+27=-4a+27