Show that the tangent at no point on the curve `y= x^3 + 3x` can be parallel to the X-axis.

Find the point on the curve y= 4x - x^2 where the tangent is parallel to-the X-axis.

Find the points at which the tangent to the curve y = x^3 -3x^2-9x+7 is parallel to the line X- axis

Find the point or points at which the tangent to the curve y=x^4/4-2x^2 is parallel to the X-axis.

If the tangent line to the curve y = f(x) at a point is parallel to the X-axis, what is the value of dy/dx ?

Find the equation of the tangent line to the curve y = x^2-2x+7 which is parallel to the 2x -y +9 = 0

Find the slope pf the tangents to the curve y = x^2 (x + 3) at the points where it crosses the X-axis

Find the point on the curve y = 2x^2 at which the slope of the tangent is 6.

Find the point on the curve y= 3x^2 - 2x +1 , at which the slope of the tangent is 4.