Greatest Integer Function linear equation

Question

Given that $2[x]=x+2(x)$, $[x]$ if the Greatest Integer Function and $(x)$ is the fractional part of $x$, find the value (s) of $x$.

I tried replacing $(x)=x–[x]$ but for an equation in $x$ and $[x]$. How do I proceed???

Answer 1

Let $x = n + r$ where $n \in \mathbb{Z}$ and $0 \le r \lt 1$. Then $[x] = n$ and $(x) = r$, so your equation becomes $2n = (n + r) + 2r \; \Rightarrow \; n = 3r$. Since $0 \le 3r \lt 3$, this gives $3$ choices for $n$ of $0, 1, 2$. You can then determine the matching values of $r$ and $x$.