So I am suppose to show that the group of upper triangular matrices in $GL_n(\mathbb{R})$ say S, is Solvable but not nilpotent.
If we define $G_1 = S$, $G_2=[G_1, G_1]$, and $G_{i+1} = [G_i, G_i]$, Then to show that $S$ is solvable if at some point we have $G_N = \{id\}$. I am unable to find $G_2$. I got some information about it. I think it should be a subset of $SL_n(\mathbb{R})$ but I am unable to determine it precisely.
Also how should I determine $G_3$, $G_4 \dots \dots$ ?