solve by factoring by grouping 5k^2-2k-7=9
\(5k^2-2k-7=9 \\ \\ 5k^2 - 2k - 7 - 9 = 0 \\ \\ 5k^2 - 2k - 16 = 0 \\ \\ 5k^2 + 8k - 10k - 16 = 0 \\ \\ k(5k + 8) - 2(5k + 8) = 0 \\ \\ (5k + 8)(k - 2) = 0 \\ \\ k = - \frac{8}{5} , 2 \\ \\\)The final result is: k = -8/5, 2.
