Laguerre Polynomials Laguerre polynomials are solutions to Laguerre's equation, a second-order linear differential equation: \$xy''+(1-x)y'+ny=0\$. For a given value of n, the solution, y, is named \$L_n(x)\$.
The polynomials can be found without calculus using recursion:
\$L_0(x)=1\$
\$L_1(x)=1-x\$
\$L_{k+1}(x)=\frac{(2k+1-x)L_k(x)-kL_{k-1}(x)}{k+1}\$
Summation can be used to the same end:
\$L_n(x)=\sum\limits_{k=0}^{n}{n\choose k}\frac{(-1)^k}{k!}x^k\$
\$L_n(x)=\sum\limits_{i=0}^n\prod\limits_{k=1}^i\frac{-(n-k+1)x}{k^2}\$
The first Laguerre polynomials are as follows:

Coefficients can be found here.
The Challenge
Given a nonnegative integer n and a real number x, find \$L_n(x)\$.
Rules

This is code-golf so the shortest answer in bytes wins.

Assume only valid input will be given.

Error should be under one ten-thousandth (±0.0001) for the test cases.


Test Cases
Here, n is the first number and x is the second.
In: 1 2
Out: -1

In: 3 1.416
Out: -0.71360922

In: 4 8.6
Out: −7.63726667

In: 6 -2.1
Out: 91.86123261
Python 2, 53 bytes

f=lambda n,x:n&lt;1or((2*n-1-x)*f(n-1,x)-~-n*f(n-2,x))/n

Try it online!