Assume that \( x \) and \( y \) are both differentiable functions of \( t \). Find the required values of \( \frac{d y}{d t} \) and \( \frac{d x}{d t} \). \[ y=\sqrt{x} \] (a) Find \( \frac{d y}{d t} \), given \( x=4 \) and \( \frac{d x}{d t}=4 \). \( \frac{d y}{d t}= \) (b) Find \( \frac{d x}{d t} \), given \( x=25 \) and \( \frac{d y}{d t}=5 \). \( \frac{d x}{d t}=\square \)
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Beyond the Answer
To solve the problem, we first need to differentiate the equation \( y = \sqrt{x} \) with respect to \( t \). (a) By using the chain rule, we get: \[ \frac{d y}{d t} = \frac{1}{2\sqrt{x}} \cdot \frac{d x}{d t} \] Now, substituting the given values where \( x = 4 \) and \( \frac{d x}{d t} = 4 \): \[ \frac{d y}{d t} = \frac{1}{2\sqrt{4}} \cdot 4 = \frac{1}{2 \cdot 2} \cdot 4 = \frac{1}{4} \cdot 4 = 1 \] Thus, \[ \frac{d y}{d t} = 1 \] (b) Now we need to find \( \frac{d x}{d t} \) using the same equation. Taking the derivative again: \[ \frac{d y}{d t} = \frac{1}{2\sqrt{x}} \cdot \frac{d x}{d t} \] Rearranging gives us: \[ \frac{d x}{d t} = 2\sqrt{x} \cdot \frac{d y}{d t} \] Substituting the values where \( x = 25 \) and \( \frac{d y}{d t} = 5 \): \[ \frac{d x}{d t} = 2\sqrt{25} \cdot 5 = 2 \cdot 5 \cdot 5 = 50 \] Therefore, \[ \frac{d x}{d t} = 50 \]