phân tích đa thức
a)\(\left(x^2+y^2-5\right)^2-4\left(x^2y^2+4xy+4\right)\)
b)\(\left(x^2+y^2+z^2\right)-4x^2y^2\)
c)\(9x^2+90x+225-\left(x-7\right)^2\)
d)\(x^2\left(x-2\right)^2-\left(x-2\right)^2-x^2+1\)
e)\(x^3-4x^2+8x-8\)
f)\(1+6x-6x^2-x^3\)