Mathematics

Mathematics

Problem

Calculate dydx∣x=π/4\left.\dfrac{dy}{dx}\right|_{x=\pi/4} when y=xx.y=x^{x}.
Intuitive explanation

The key here is recognizing that xxx^x isn't a simple power or exponential—it's a variable base raised to a variable exponent. Rewrite it using logarithms: y=exln⁡xy = e^{x \ln x}, which lets you use the chain rule on a familiar form. Once you differentiate, you'll find that dydx\frac{dy}{dx} involves a factor of xxx^x itself, which makes plugging in x=π/4x = \pi/4 straightforward.

Intuitive explanation

The key here is recognizing that xxx^x isn't a simple power or exponential—it's a variable base raised to a variable exponent. Rewrite it using logarithms: y=exln⁡xy = e^{x \ln x}, which lets you use the chain rule on a familiar form. Once you differentiate, you'll find that dydx\frac{dy}{dx} involves a factor of xxx^x itself, which makes plugging in x=π/4x = \pi/4 straightforward.

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