\(8x^3-216=\left(2x\right)^3-6^3=(*)\\--------------------------\\use:a^3-b^3=(a-b)(a^2+ab+b^2)\\--------------------------\\\\(*)=(2x-6)[(2x)^2+2x\times6+6^2]=\boxed{(2x-6)(4x^2+12x+36)}\\\\========================================\)
\(Other:\\\\8x^3-216=8(x^3-27)=8(x^3-3^3)=8(x-3)(x^2-3x+3^2)\\\\=\boxed{8(x-3)(x^2-3x+9)}\)
