\(c,9x^4+4x^2y^4-12x^3y^2=x^2\left(9x^2-12xy^2+4y^4\right)=x^2\left(3x-2y^2\right)^2\\ d,-x^3+8y^3-12xy^2+6x^2y=-\left(x-2y\right)^2\\ f,\left(2x-1\right)^2+\left(2-4x\right)\left(x+1\right)+\left(x+1\right)^2\\ =\left(2x-1\right)^2-2\left(2x-1\right)\left(x+1\right)+\left(x+1\right)^2\\ =\left(2x-1-x-1\right)^2=\left(x-2\right)^2\)
\(d,16x^2y^2-x^4y^2-16y^2\\ =-y^2\left(x^4-16x^2+16\right)\\ =-y^2\left[\left(x^2-8\right)^2-48\right]\\ =-y^2\left(x^2-4\sqrt{3}-8\right)\left(x^2+4\sqrt{3}-8\right)\\ e,27x^3-64y^3+36xy\left(4y-3x\right)\\ =27x^3-64y^3+144xy^2-108x^2y\\ =\left(3x-4y\right)^3\\ g,a^4+2a^3+5a^2+4a+4\\ =\left(a^4+2a^3+a^2\right)+\left(a^2+4a+4\right)\\ =a^2\left(a+1\right)^2+\left(a+2\right)^2\)
