1.X^2n - 3X^n
=x^(n+n)-3x^n
=x^n(x^n -3)
2.(X-2Y)-(X-2Y)^3
=(x-2y)[1-(x-2y)²]
=(x-2y)(1-x+2y)(1+x-2y)
3.6ab(a+b)^2 -4a^2b(a+b)
=2ab(a+b)[3(a+b)-2a]
=2ab(a+3b)(a+b)
4.X^n+2 - 2X^2
=x²(x^n-2)