Practicing Success
If $x=t^3, y=t^4$ then $\frac{d^2 y}{d x^2}$ at $t=2$ is |
$\frac{8}{3}$ $\frac{1}{9}$ $\frac{2}{9}$ $\frac{9}{16}$ |
$\frac{1}{9}$ |
$x=t^3$ $y=t^4$ $\frac{d x}{d t}=3 t^2$ $\frac{d y}{d t}=4 t^3$ $\Rightarrow \frac{d y / d t}{d x / d t}=\frac{4 t^3}{3 t^2}$ $\Rightarrow \frac{d y}{d x}=\frac{4 t}{3}$ so $\frac{d^2 y}{d x^2}=\frac{4}{3} \frac{d t}{d x}$ $\Rightarrow \frac{d^2 y}{d x^2}=\frac{4}{3 \times 3 t^2}=\frac{4}{9 t^2}$ so at t = 2 $\Rightarrow \frac{4}{9 \times(2)^2}$ $=\frac{1}{9}$ |