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Question

Question: Derivatives of. 1/undroot x square - 1...

Derivatives of. 1/undroot x square - 1

Answer

The derivative of 1x21\frac{1}{\sqrt{x^2 - 1}} is x(x21)3/2-\frac{x}{(x^2 - 1)^{3/2}}.

Explanation

Solution

The problem asks for the derivative of the function y=1x21y = \frac{1}{\sqrt{x^2 - 1}}.

Explanation:

  1. Rewrite the function: The given function can be written in exponential form: y=(x21)1/2y = (x^2 - 1)^{-1/2}

  2. Apply the Chain Rule: Let u=x21u = x^2 - 1. Then y=u1/2y = u^{-1/2}. The chain rule states dydx=dydududx\frac{dy}{dx} = \frac{dy}{du} \cdot \frac{du}{dx}.

    • Find dydu\frac{dy}{du}: dydu=ddu(u1/2)=12u1/21=12u3/2\frac{dy}{du} = \frac{d}{du}(u^{-1/2}) = -\frac{1}{2} u^{-1/2 - 1} = -\frac{1}{2} u^{-3/2}
    • Find dudx\frac{du}{dx}: dudx=ddx(x21)=2x\frac{du}{dx} = \frac{d}{dx}(x^2 - 1) = 2x
  3. Combine the derivatives: dydx=(12u3/2)(2x)\frac{dy}{dx} = \left(-\frac{1}{2} u^{-3/2}\right) \cdot (2x)

  4. Substitute back u=x21u = x^2 - 1 and simplify: dydx=12(x21)3/2(2x)\frac{dy}{dx} = -\frac{1}{2} (x^2 - 1)^{-3/2} \cdot (2x) dydx=x(x21)3/2\frac{dy}{dx} = -x (x^2 - 1)^{-3/2}

  5. Express in radical form (optional): dydx=x(x21)3/2\frac{dy}{dx} = -\frac{x}{(x^2 - 1)^{3/2}} or dydx=x(x21)3\frac{dy}{dx} = -\frac{x}{\sqrt{(x^2 - 1)^3}}