lim x is approaching 1 r^2-r/ 2r^2+5r-7
I have no clue how to get this problem started.

Always look to factor something and cancel if necessary.

\lim_{r\to 1}\frac{r^{2}-r}{2r^{2}+5r-7}

\lim_{r\to 1}\frac{r\sout{(r-1)}}{\sout{(r-1)}(2r+7)}

Now, see it?