Given the parametric equations x = t 2 + 2 and y = t 3 − 4t, where −3 ≤ t ≤ 3, which of the following graphs represents the curve and its orientation?

Given the parametric equations x t 2 2 and y t 3 4t where 3 t 3 which of the following graphs represents the curve and its orientation class=

Respuesta :

Hello there. To solve this question, we'll have to remember some properties about orientation of parametric curves and how to determine their graphs.

First, given the parametric equations:

[tex]\begin{gathered} x=t^2+2 \\ y=t^3-4t \end{gathered}[/tex]

We can solve the first equation for t, such that:

[tex]\begin{gathered} t^2+2=x \\ t^2=x-2 \\ t=\pm\sqrt[]{x-2} \end{gathered}[/tex]

Since t is between - 3 and 3, we have to analyze which values of x are possible using the end points:

(-3)² + 2 = 3² + 2 = 9 + 2 = 11

So as you can see, the values of x are

[tex]2\le x\le11[/tex]

Plugging the first solution into the equation for y, we have

[tex]\begin{gathered} _{}y=(\sqrt[]{x-2})^3-4\sqrt[]{x-2}_{} \\ y=(x-6)\sqrt[]{x-2} \end{gathered}[/tex]

And as x is between 2 and 11, we get that y is between

[tex]-15\le y\le15[/tex]

Sketching this curve, we have

With the other solution, we get

[tex]\begin{gathered} _{}y=(-\sqrt[]{x-2})^3-4\cdot(-\sqrt[]{x-2}) \\ y=-(x-2)\sqrt[]{x-2}+4\sqrt[]{x-2} \\ y=(6-x)\sqrt[]{x-2} \end{gathered}[/tex]

The two curves together looks like

Finally, we have to determine the orientation

For this, let's take a point in the first solution, say we take t = 1 then t = 2

Plugging it into the equations, we get

[tex]\begin{gathered} x=1^2+2=1+2=3 \\ y=1^3-4\cdot1=-3 \end{gathered}[/tex]

Now with t = 2

[tex]\begin{gathered} x=2^2+2=4+2=6 \\ y=2^3-4\cdot2=0 \end{gathered}[/tex]

So as t increses, we go from:

So this is the orientation of the curve and it is the answer contained in the fourth option.

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