urgent-F.2 maths

yo
my teacher also said this:
16x^3-4x-48

ans:
if 8x^3-27
=(2x-3)(4x^2+6x+9)
16^3-4x-48
=4(4x^3-x-12)
=4(4x^3-9x+8x-12)
=4[x(4x^2-9)+8x-12]
=4{x[(2x)^2-3^2]+4(2x-3)}
=4{x[2x-3][2x+3]+4(2x-3)}
=4{[4x^2+3x+4][2x-3]}