`81x(x-1)^{2}-4x^{3}`
`=x[81(x-1)^{2}-4x^{2}]`
`=x{[9(x-1)]^{2}-(2x)^{2}}`
`=x[(9x-9)^{2}-(2x)^{2}]`
`=x(9x-9-2x)(9x-9+2x)`
`=x(7x-9)(11x-9)`
81x(x−1)2−4x381x(x-1)2-4x3
=x[81(x−1)2−4x2]=x[81(x-1)2-4x2]
=x{[9(x−1)]2−(2x)2}=x{[9(x-1)]2-(2x)2}
=x[(9x−9)2−(2x)2]=x[(9x-9)2-(2x)2]
=x(9x−9−2x)(9x−9+2x)=x(9x-9-2x)(9x-9+2x)
=x(7x−9)(11x−9)