Rút gọn các biểu thức sau:
A. \(\left(a^2+a-1\right)\left(a^2-a+1\right)\)
B. \(\left(a+2\right)\left(a-2\right)\left(a^2+2a+4\right)\left(a^2-2a+4\right)\)
C, \(\left(2+3y\right)^2-\left(2x-3y\right)^2-12xy\)
D. \(\left(x+1\right)^3-\left(x-1\right)^3-\left(x^3-1\right)-\left(x-1\right)\left(x^2+x+1\right)\)