Q. The slope of the tangent to the curve $x = 3t^{2} + 1,\ y = t^{3} - 1$, at $x = 1$is

A) 0
B) $\frac{1}{2}$
C) $\infty$
D) $- 2$
Explanation

(a)
Given curve is $x = 3t^{2} + 1,\ y = t^{3} - 1$
For $x = 1,\ \ 3t^{2} + 1 = 1\ \ \ \Rightarrow \ \ t = 0$
$\therefore\ \ \frac{dx}{dt} = 6t,\ \frac{dy}{dx} = 3t^{2}$
Now, $\frac{dy}{dx} = \left( \frac{\frac{dy}{dt}}{\frac{dx}{dt}} \right) = \frac{3t^{2}}{6t} = \frac{t}{2}$
$\therefore\ \ \left( \frac{dy}{dx} \right)_{(t = 0)} = \frac{0}{2} = 0$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.