I need help with this one.

Find the tangent lines to the ellipse x^2 + 2y^2 +4x = 5 at the point (1,0)

I differentiated the equation implicitly to get this: (-2x-4)/4y

And im stuck here. cuz i get a ZERO in the denoinator.

the teacher said something like this is gonna appear on the test, so please help!!!