Math Problem Statement

(b) Find the derivatives of the following:

(i) y = sqrt((a ^ 2 - x ^ 2)/(a ^ 2 + x ^ 2))

Solution

We will differentiate y=a2x2a2+x2y = \sqrt{\frac{a^2 - x^2}{a^2 + x^2}} with respect to xx.

Step-by-step solution:

Step 1: Rewrite the equation

The given function is: y=a2x2a2+x2y = \sqrt{\frac{a^2 - x^2}{a^2 + x^2}} Let u=a2x2a2+x2u = \frac{a^2 - x^2}{a^2 + x^2}. Then, y=uy = \sqrt{u}.

Step 2: Differentiate y=uy = \sqrt{u}

The derivative of y=uy = \sqrt{u} is: dydx=12ududx.\frac{dy}{dx} = \frac{1}{2\sqrt{u}} \cdot \frac{du}{dx}.

Step 3: Differentiate u=a2x2a2+x2u = \frac{a^2 - x^2}{a^2 + x^2}

Use the quotient rule: dudx=(a2+x2)ddx(a2x2)(a2x2)ddx(a2+x2)(a2+x2)2.\frac{du}{dx} = \frac{(a^2 + x^2) \cdot \frac{d}{dx}(a^2 - x^2) - (a^2 - x^2) \cdot \frac{d}{dx}(a^2 + x^2)}{(a^2 + x^2)^2}. Simplify each derivative:

  • ddx(a2x2)=2x\frac{d}{dx}(a^2 - x^2) = -2x,
  • ddx(a2+x2)=2x\frac{d}{dx}(a^2 + x^2) = 2x.

Substitute these into the quotient rule: dudx=(a2+x2)(2x)(a2x2)(2x)(a2+x2)2.\frac{du}{dx} = \frac{(a^2 + x^2)(-2x) - (a^2 - x^2)(2x)}{(a^2 + x^2)^2}.

Simplify the numerator:

= -2x(a^2 + x^2 + a^2 - x^2) = -2x(2a^2).$$ Thus: $$\frac{du}{dx} = \frac{-4xa^2}{(a^2 + x^2)^2}.$$ #### Step 4: Substitute back into $$\frac{dy}{dx}$$ Now substitute $$\frac{du}{dx}$$ and $$u = \frac{a^2 - x^2}{a^2 + x^2}$$ into $$\frac{dy}{dx}$$: $$\frac{dy}{dx} = \frac{1}{2\sqrt{\frac{a^2 - x^2}{a^2 + x^2}}} \cdot \frac{-4xa^2}{(a^2 + x^2)^2}.$$ Simplify: $$\frac{dy}{dx} = \frac{-4xa^2}{2\sqrt{\frac{a^2 - x^2}{a^2 + x^2}} \cdot (a^2 + x^2)^2}.$$ Combine terms: $$\frac{dy}{dx} = \frac{-2xa^2}{(a^2 + x^2) \sqrt{(a^2 - x^2)(a^2 + x^2)}}.$$ ### Final Answer: $$\frac{dy}{dx} = \frac{-2xa^2}{(a^2 + x^2) \sqrt{a^4 - x^4}}.$$ Would you like me to clarify or expand further? ### Related Questions: 1. How is the chain rule applied in this problem? 2. Can you explain the quotient rule in more detail? 3. What are the limitations of this derivative when $$x \to \pm a$$? 4. How does this derivative behave as $$x \to \infty$$? 5. Could we rewrite the expression in terms of trigonometric functions for a simpler form? **Tip:** Always simplify radicals and fractions separately to avoid confusion in multi-step derivatives.

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Math Problem Analysis

Mathematical Concepts

Calculus
Differentiation
Quotient Rule
Chain Rule
Radical Functions

Formulas

Derivative of sqrt(u): dy/dx = (1 / (2sqrt(u))) * du/dx
Quotient Rule: (f/g)' = (g*f' - f*g') / g^2

Theorems

Quotient Rule
Chain Rule

Suitable Grade Level

Grade 11-12 or early college calculus