find the equations of the tangent lines to $\displaystyle f(x)=4x-x^2$ as they both pass thru point $\displaystyle (2,5) $which is not on the graph.

$\displaystyle

f'(x) = 4-2x

$

but we do not the points on the graph where the 2 lines from this point will be tangent. we know the slope of line will be same as $\displaystyle 4-2x $

anyway not seeing how this these 2 equations are derived

appreceiate much..