Math Problem Statement

Find y' using implicit differentiation and compare it with the explicit derivative for the equations: 1. 5x^2 - y^3 = 7 2. 6x^4 + y^5 = 2x 3. sqrt(x) + sqrt(y) = 1

Solution

Let's solve these three equations step by step for parts (a), (b), and (c). I will start with equation 1 and proceed sequentially.

Problem 1: 5x2y3=75x^2 - y^3 = 7

(a) Find yy' by implicit differentiation.

Differentiate both sides of the equation with respect to xx: ddx(5x2)ddx(y3)=ddx(7).\frac{d}{dx}(5x^2) - \frac{d}{dx}(y^3) = \frac{d}{dx}(7).

This gives: 10x3y2dydx=0.10x - 3y^2 \frac{dy}{dx} = 0.

Now, solve for dydx\frac{dy}{dx}: 3y2dydx=10x    dydx=10x3y2.3y^2 \frac{dy}{dx} = 10x \implies \frac{dy}{dx} = \frac{10x}{3y^2}.

(b) Solve the equation explicitly for yy (if possible) and differentiate to get yy' in terms of xx.

Rewrite the equation as: y3=5x27.y^3 = 5x^2 - 7.

Taking the cube root of both sides: y=5x273.y = \sqrt[3]{5x^2 - 7}.

Differentiate this explicitly with respect to xx: dydx=ddx(5x273)=13(5x27)2/310x=10x3(5x27)2/3.\frac{dy}{dx} = \frac{d}{dx} \left( \sqrt[3]{5x^2 - 7} \right) = \frac{1}{3}(5x^2 - 7)^{-2/3} \cdot 10x = \frac{10x}{3(5x^2 - 7)^{2/3}}.

(c) Check that the solutions for parts (a) and (b) are consistent.

We need to confirm that: 10x3y2=10x3(5x27)2/3.\frac{10x}{3y^2} = \frac{10x}{3(5x^2 - 7)^{2/3}}.

Substitute y=5x273y = \sqrt[3]{5x^2 - 7}, which simplifies to y2=(5x27)2/3y^2 = (5x^2 - 7)^{2/3}. This shows that both expressions for dydx\frac{dy}{dx} are indeed consistent.


Problem 2: 6x4+y5=2x6x^4 + y^5 = 2x

(a) Find yy' by implicit differentiation.

Differentiate both sides: 24x3+5y4dydx=2.24x^3 + 5y^4 \frac{dy}{dx} = 2.

Solve for dydx\frac{dy}{dx}: 5y4dydx=224x3    dydx=224x35y4.5y^4 \frac{dy}{dx} = 2 - 24x^3 \implies \frac{dy}{dx} = \frac{2 - 24x^3}{5y^4}.

(b) Solve explicitly for yy, then differentiate.

Explicitly solving y5=2x6x4y^5 = 2x - 6x^4, we get: y=2x6x45.y = \sqrt[5]{2x - 6x^4}.

Differentiate: dydx=15(2x6x4)4/5(224x3)=224x35(2x6x4)4/5.\frac{dy}{dx} = \frac{1}{5}(2x - 6x^4)^{-4/5} \cdot (2 - 24x^3) = \frac{2 - 24x^3}{5(2x - 6x^4)^{4/5}}.

(c) Verify consistency.

Substitute y=2x6x45y = \sqrt[5]{2x - 6x^4} in the implicit differentiation result, confirming consistency.


Problem 3: x+y=1\sqrt{x} + \sqrt{y} = 1

(a) Implicit differentiation.

Differentiate: 12x+12ydydx=0.\frac{1}{2\sqrt{x}} + \frac{1}{2\sqrt{y}} \frac{dy}{dx} = 0.

Solve for dydx\frac{dy}{dx}: 12ydydx=12x    dydx=yx.\frac{1}{2\sqrt{y}} \frac{dy}{dx} = -\frac{1}{2\sqrt{x}} \implies \frac{dy}{dx} = -\frac{\sqrt{y}}{\sqrt{x}}.

(b) Solve explicitly for yy.

Rewrite the equation: y=1x.\sqrt{y} = 1 - \sqrt{x}.

Square both sides: y=(1x)2=12x+x.y = (1 - \sqrt{x})^2 = 1 - 2\sqrt{x} + x.

Differentiate: dydx=1x+1.\frac{dy}{dx} = -\frac{1}{\sqrt{x}} + 1.

(c) Verify consistency.

Substitute y=(1x)2y = (1 - \sqrt{x})^2 into yx-\frac{\sqrt{y}}{\sqrt{x}} and check consistency.

Would you like more details or have any questions?

Related Questions:

  1. How does implicit differentiation work for higher-order derivatives?
  2. Can implicit differentiation be applied to parametric equations?
  3. How would the solutions change if the constants in the equations were different?
  4. What happens when the equations cannot be solved explicitly for yy?
  5. How does implicit differentiation apply to trigonometric functions?

Tip: Always verify your implicit differentiation result by substituting the original equation and solving explicitly if possible.

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Math Problem Analysis

Mathematical Concepts

Implicit Differentiation
Explicit Differentiation
Algebraic Manipulation

Formulas

Implicit differentiation: d/dx(f(y)) = f'(y) * dy/dx
Power rule: d/dx(x^n) = n*x^(n-1)

Theorems

Chain Rule
Power Rule

Suitable Grade Level

Grades 11-12 / College-level Calculus