What is the coefficient of in
Replace (x^4 + x^3 + x^2) with m, and (x + 1) with u, then we have
(m + u)^4
Expanding this gives,
m^4 + 4.m^3.u + 6.m^2.u^2 + 4.m.u^3 + u^4
every term above, when expanded, will have all constituent terms with powers of x greater than 2, except for the last term, u^4.
expanding u^4 = (x + 1)^4 = x^4 + 4x^3 + 6x^2 + 4x + 1
Coefficient of x in the expansion of the original expression is: 4