a: \(=64x^3-96x^2y+48xy^2-8y^3-x\left(x^2-9y^2\right)-4x^2y+8x^2\)
\(=64x^3-100x^2y+48xy^2-8y^3+8x^2-x^3+9xy^2\)
\(=64x^3-8y^3-100x^2y+57xy^2+8x^2\)
b: \(=x^2+6x+9-10\left(x^2+2x-3\right)+25\left(x^2-2x+1\right)\)
\(=x^2+6x+9-10x^2-20x+30+25x^2-50x+25\)
\(=16x^2-64x+64\)


