Help with symbolics, how to get coefficients and simple roots

New to Julia
#1 
using Symbolics

@variables x
D = Differential(x)
Z = 2.1309 + 0.0515x - 0.0009(x^2)
ZZ = expand_derivatives(D(Z))

# Derivative is 0.0515 - 0.0018x
println("Derivative is ",ZZ)

# How to get the coefficient of x from equation ZZ

# Question 1, how do I get the coefficient of x^0 which is 0.0515
#coefficient_x0 = ???

# Question 2, how do I get the coefficient of x^1 which is -0.0018
#coefficient_x1 = ???

# question 3, How do I find the root of the derivative which is 28.611
# derivative_root = ???

How to extract the coefficients of x from ZZ dynamically?

#2

I think someone recently asked for a coeff function but it doesn’t exist yet.

Linear rootfinding is done via solve_for.