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Multiple Choice
Find the derivative of the function: .
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Verified step by step guidance
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Step 1: Recognize that the function y = arctan(\frac{1 - x}{1 + x}) involves the arctan function, which has a derivative formula. Recall that the derivative of arctan(u) with respect to x is \frac{du/dx}{1 + u^2}.
Step 2: Identify u = \frac{1 - x}{1 + x} as the argument of the arctan function. To apply the derivative formula, first compute the derivative of u with respect to x. Use the quotient rule: \frac{d}{dx}\left(\frac{1 - x}{1 + x}\right) = \frac{(1 + x)(-1) - (1 - x)(1)}{(1 + x)^2}.
Step 3: Simplify the numerator of the derivative of u. Combine terms: (-1)(1 + x) - (1)(1 - x) = -1 - x - 1 + x = -2. Thus, \frac{du}{dx} = \frac{-2}{(1 + x)^2}.
Step 4: Substitute \frac{du}{dx} and u = \frac{1 - x}{1 + x} into the derivative formula for arctan(u). The derivative becomes \frac{-2}{(1 + x)^2} / \left(1 + \left(\frac{1 - x}{1 + x}\right)^2\right).
Step 5: Simplify the denominator 1 + \left(\frac{1 - x}{1 + x}\right)^2. Square \frac{1 - x}{1 + x} to get \frac{(1 - x)^2}{(1 + x)^2}, then add 1: \frac{(1 + x)^2 + (1 - x)^2}{(1 + x)^2}. Combine this with the numerator \frac{-2}{(1 + x)^2} to get the final derivative expression: \frac{-2}{(1 + x)^2 + (1 - x)^2}.