Math Problem Statement

(x^2 + y^2)^2 = 2(x^2 - y^2), find dy/dx.

Solution

The image shows a step-by-step differentiation process of the given equation using implicit differentiation. Let's walk through the steps:

Given Equation:

(x2+y2)2=2(x2y2)(x^2 + y^2)^2 = 2(x^2 - y^2)

Step 1: Apply Implicit Differentiation

Both sides of the equation are implicitly differentiated with respect to xx.

Left-hand side:

2(x2+y2)ddx(x2+y2)2(x^2 + y^2) \cdot \frac{d}{dx}(x^2 + y^2)

The chain rule is applied here, where (x2+y2)2(x^2 + y^2)^2 is first differentiated as 2(x2+y2)2(x^2 + y^2), and then (x2+y2)(x^2 + y^2) is differentiated. The derivative of x2+y2x^2 + y^2 is:

ddx(x2+y2)=2x+2ydydx\frac{d}{dx}(x^2 + y^2) = 2x + 2y\frac{dy}{dx}

So, the left-hand side becomes: 2(x2+y2)(2x+2ydydx)2(x^2 + y^2)(2x + 2y\frac{dy}{dx})

Right-hand side:

ddx(2(x2y2))=2(2x2ydydx)\frac{d}{dx}(2(x^2 - y^2)) = 2(2x - 2y\frac{dy}{dx})

Step 2: Combine and Simplify

Now we equate the derivatives of both sides: 2(x2+y2)(2x+2ydydx)=2(2x2ydydx)2(x^2 + y^2)(2x + 2y\frac{dy}{dx}) = 2(2x - 2y\frac{dy}{dx})

Divide both sides by 2: (x2+y2)(2x+2ydydx)=2x2ydydx(x^2 + y^2)(2x + 2y\frac{dy}{dx}) = 2x - 2y\frac{dy}{dx}

Step 3: Expand the Equation

Expand both sides: 2x(x2+y2)+2y(x2+y2)dydx=2x2ydydx2x(x^2 + y^2) + 2y(x^2 + y^2)\frac{dy}{dx} = 2x - 2y\frac{dy}{dx}

Step 4: Collect dydx\frac{dy}{dx} terms

Move all terms with dydx\frac{dy}{dx} to one side: 2y(x2+y2)dydx+2ydydx=2x2x(x2+y2)2y(x^2 + y^2)\frac{dy}{dx} + 2y\frac{dy}{dx} = 2x - 2x(x^2 + y^2)

Factor out dydx\frac{dy}{dx}: dydx[2y(x2+y2)+2y]=2x(1x2y2)\frac{dy}{dx} [2y(x^2 + y^2) + 2y] = 2x(1 - x^2 - y^2)

Step 5: Solve for dydx\frac{dy}{dx}

dydx=2x(1x2y2)2y(x2+y2+1)\frac{dy}{dx} = \frac{2x(1 - x^2 - y^2)}{2y(x^2 + y^2 + 1)}

This is the expression for dydx\frac{dy}{dx}.

Final Part:

The question at the end asks about the condition under which dydx=0\frac{dy}{dx} = 0. This happens when the numerator is zero: 2x(1x2y2)=02x(1 - x^2 - y^2) = 0

Thus, x=0x = 0 or x2+y2=1x^2 + y^2 = 1.

Would you like more details, or do you have any questions about these steps?

5 Related Questions:

  1. What is implicit differentiation and how does it differ from regular differentiation?
  2. How does the chain rule apply when differentiating expressions involving both xx and yy?
  3. What happens to the derivative when x2+y2=1x^2 + y^2 = 1?
  4. Why is it important to collect like terms when solving for dydx\frac{dy}{dx}?
  5. How does setting dydx=0\frac{dy}{dx} = 0 help find critical points in the function?

Tip:

When dealing with implicit differentiation, always remember to apply the chain rule carefully, especially when differentiating terms involving yy, as they implicitly depend on xx.

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Math Problem Analysis

Mathematical Concepts

Implicit Differentiation
Chain Rule
Algebraic Manipulation

Formulas

Implicit Differentiation: d/dx[f(y)] = f'(y) * dy/dx
Chain Rule: d/dx[f(g(x))] = f'(g(x)) * g'(x)

Theorems

Chain Rule
Implicit Differentiation

Suitable Grade Level

Undergraduate Calculus