The standard form:
[tex]f(x)=ax^3+bx^2+cx+d[/tex]
Use:[tex](a-b)(a+b)=a^2-b^2\\\\(a+b)(c+d)=ab+ad+bc+bd\\\\a^n\cdot a^m=a^{n+m}[/tex]
[tex]f(x)=(2x+1)(x+1)(x-1)\\\\f(x)=(2x+1)(x^2-1^2)\\\\f(x)=(2x+1)(x^2-1)\\\\f(x)=2x\cdot x^2-2x\cdot1+1\cdotx^2-1\cdot1\\\\f(x)=2x^3-2x+x^2-1\\\\\boxed{f(x)=2x^3+x^2-2x-1}[/tex]
