Find [tex]\(\frac{dy}{dx}\)[/tex] in terms of [tex]\(a\)[/tex] if [tex]\(x = a t^2\)[/tex] and [tex]\(y = 2at\)[/tex].

A. [tex]\(\frac{1}{t}\)[/tex]
B. [tex]\(-\frac{1}{t}\)[/tex]
C. [tex]\(\frac{2}{t}\)[/tex]
D. [tex]\(t\)[/tex]



Answer :

To find [tex]\(\frac{dy}{dx}\)[/tex] given the parametric equations [tex]\(x = a t^2\)[/tex] and [tex]\(y = 2at\)[/tex], we'll follow a systematic approach.

1. Express [tex]\(x\)[/tex] and [tex]\(y\)[/tex] in terms of [tex]\(t\)[/tex]:
[tex]\[ x = a t^2 \][/tex]
[tex]\[ y = 2a t \][/tex]

2. Calculate the derivatives [tex]\(\frac{dx}{dt}\)[/tex] and [tex]\(\frac{dy}{dt}\)[/tex]:

- Differentiating [tex]\(x\)[/tex] with respect to [tex]\(t\)[/tex]:
[tex]\[ \frac{dx}{dt} = \frac{d}{dt}(a t^2) = 2at \][/tex]

- Differentiating [tex]\(y\)[/tex] with respect to [tex]\(t\)[/tex]:
[tex]\[ \frac{dy}{dt} = \frac{d}{dt}(2at) = 2a \][/tex]

3. Find [tex]\(\frac{dy}{dx}\)[/tex] using the chain rule:
[tex]\[ \frac{dy}{dx} = \frac{\frac{dy}{dt}}{\frac{dx}{dt}} \][/tex]

4. Substitute the derivatives [tex]\(\frac{dy}{dt}\)[/tex] and [tex]\(\frac{dx}{dt}\)[/tex] into the equation:
[tex]\[ \frac{dy}{dx} = \frac{2a}{2at} = \frac{2a}{2at} = \frac{1}{t} \][/tex]

Therefore, the answer is:
[tex]\[ \frac{dy}{dx} = \frac{1}{t} \][/tex]

So, the correct choice is (a) [tex]\(\frac{1}{t}\)[/tex].