the "b" of the equation of the tangent is the y-coordinate of the tangent point. The tangent point must be situated on the given curve. Therefore calculate first the coordinates of the tangent point.
You know already that the x-coordinate of the tangent point is x = 1. Plug in this value into the given equation:
That means you have 2 points which satisfy the conditions:
Plug in the values of the coordinates into the equation of the dy/dx to calculate the slope of the tangents.