Collecting the terms in a specific coefficient

Hi, I want to ask how we can make Matlab do such a thing;

For ex; I have an expression ----> a*x^2+2*a^3*x

and I want this expression comes -----> x(a(x+2a^2))

I found a command named horner but horner only collects the terms for x or y but I want the expression nested for a or any specific term I say.

Thanks for your help

Answer 1

[Andrei Bobrov]

syms a x 
factor(a*x^2+2*a^3*x)

[Kazim]

Thank you very much Andrei