Factorials of the Plane!

Calculus Level 1

Let $x$ be a real number satisfying $x! + (x-1)! = 3x(x-1)!$ , find the value of $4x$ .

To clarify, $x! = \Gamma(x + 1)$ , where $\Gamma(\cdot)$ denotes the gamma function. In other words, even if $x$ is not an integer, $x!$ can be computed.