Approximate the area under the curve $f(x) = x^2+4x+6$ on the interval $[2,6]$ using the right-hand Riemann sum where $P$ is the partition of $[2,6]$ determined by $\{2,4,5,6\}$
I set up the right Riemann sum $f(3)+f(4)+f(5)+f(6)$ but I don't understand what the partition or the values $\{2,4,5,6\}$ are used for.