The value of the derivative of the Sigmoid function given by f(x) = 1 1+e−2x at x=0 is

1. A0
2. B1/2
3. C1/4
4. D∞

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Correct answer: B. 1/2

Explanation

For f(x) = 1/(1 + e^(−2x)), f′(x) = 2f(1 − f). At x = 0, f = 1/2, so f′ = 2 × 1/2 × 1/2 = 1/2.