The points at which the tangents to the curve y = x3 – 12x + 18 are parallel to x-axis are:

Given the equation of the curve is


y = x3 – 12x + 18


Differentiating on both sides with respect to x, we get



Applying the sum rule of differentiation, we get



We know derivative of a constant is 0, so above equation becomes



Applying the power rule we get



So, the slope of line parallel to the x-axis is given by



So equating equation (i) to 0, we get


3x2-12=0


3x2=12


x2=4


x=±2


When x=2, the given equation of curve becomes,


y = x3 – 12x + 18


y = (2)3 – 12(2) + 18


y = 8– 24 + 18


y = 2


When x=-2, the given equation of curve becomes,


y = x3 – 12x + 18


y = (-2)3 – 12(-2) + 18


y = -8+24 + 18


y = 34


Hence the points at which the tangents to the curve y = x3 – 12x + 18 are parallel to x-axis are (2, 2) and (-2, 34).


So the correct option is option D.

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