Suppose that $f$ is a function given as $f(x) = \frac{1}{2}x^2 + 2x + 5$. Find the equation of all tangent lines drawn to the graph of $f$ from the point $P(3, 7)$. Enter the slope of the tangent lines. If there are more than one tangent lines, enter the slopes separated by a comma. If there is no tangent line, enter DNE. m =