I want to use maple to solve the following recursive inhomogenous equation:

X_n+2 - 5x_n+1 6x_n = 4n+1

I thought I could write like this:

 but it doesn't work. I get the error message

"Error, (in rsolve/single) equation false = 0 does not involve function F()"

How should I write in order to solve it?

How do I do to get a single number (decimal) when I evaluate an input.

For example, I write this:

evalf((546, 1/1000000000)*(7, 0)*sqrt(36+1/(7, 0)^2));

but I still get the same thing as I inputed as a response, how do I do to get an actual number?