13) Find points on the curve at which the tangents are (b) parallel to y-axis
Parallel to y-axis means the slope of the tangent is , means the slope of normal is 0
We know that slope of the tangent at a given point on the given curve is given by
Given the equation of the curve is
Slope of normal =
From this we can say that y = 0
Now. when y = 0,
Hence, the coordinates are (3,0) and (-3,0)