The equation of the given curve is 
The slope of the tangents to the given curve at any point (x, y) is given by,
If the slope of the tangent is −1, then we have:
Thus, there are two tangents to the given curve having slope −1. These are passing through the points (0, −1) and (2, 1).
The equation of the tangent through (0, −1) is given by,
The equation of the tangent through (2, 1) is given by,
y − 1 = −1 (x − 2)
⇒ y − 1 = − x + 2
⇒ y + x − 3 = 0
Hence, the equations of the required lines are y + x + 1 = 0 and y + x − 3 = 0.
