Math Problem Statement

Find the slope of the line tangent to the curve x^3 + xy + y^3 = 5 at the point (-1, 2) and find dy/dx if x^2y + y^2x = -2.

Solution

Let’s solve the two problems from the uploaded image step by step.


Problem 1:

Find the slope of the tangent line to the curve x3+xy+y3=5x^3 + xy + y^3 = 5 at the point (1,2)(-1, 2).

Step 1: Differentiate the given equation implicitly

The given equation is: x3+xy+y3=5x^3 + xy + y^3 = 5 Taking the derivative of both sides with respect to xx, we get: ddx(x3)+ddx(xy)+ddx(y3)=ddx(5)\frac{d}{dx}(x^3) + \frac{d}{dx}(xy) + \frac{d}{dx}(y^3) = \frac{d}{dx}(5) Using the chain rule and the product rule: 3x2+(xdydx+y)+3y2dydx=03x^2 + \left( x\frac{dy}{dx} + y \right) + 3y^2\frac{dy}{dx} = 0

Step 2: Simplify to isolate dydx\frac{dy}{dx}

Reorganizing terms: xdydx+3y2dydx=3x2yx\frac{dy}{dx} + 3y^2\frac{dy}{dx} = -3x^2 - y Factor dydx\frac{dy}{dx} on the left-hand side: dydx(x+3y2)=3x2y\frac{dy}{dx} (x + 3y^2) = -3x^2 - y Solve for dydx\frac{dy}{dx}: dydx=3x2yx+3y2\frac{dy}{dx} = \frac{-3x^2 - y}{x + 3y^2}

Step 3: Evaluate dydx\frac{dy}{dx} at (1,2)(-1, 2)

Substitute x=1x = -1 and y=2y = 2: dydx=3(1)221+3(2)2\frac{dy}{dx} = \frac{-3(-1)^2 - 2}{-1 + 3(2)^2} Simplify: dydx=3(1)21+3(4)\frac{dy}{dx} = \frac{-3(1) - 2}{-1 + 3(4)} dydx=321+12\frac{dy}{dx} = \frac{-3 - 2}{-1 + 12} dydx=511\frac{dy}{dx} = \frac{-5}{11}

Thus, the slope of the tangent line is: 511\boxed{-\frac{5}{11}}


Problem 2:

Find dydx\frac{dy}{dx} if x2y+y2x=2x^2y + y^2x = -2.

Step 1: Differentiate the given equation implicitly

The given equation is: x2y+y2x=2x^2y + y^2x = -2 Differentiate both sides with respect to xx: ddx(x2y)+ddx(y2x)=ddx(2)\frac{d}{dx}(x^2y) + \frac{d}{dx}(y^2x) = \frac{d}{dx}(-2) Using the product rule: (2x)y+x2dydx+(2y)dydxx+y2=0(2x)y + x^2\frac{dy}{dx} + (2y)\frac{dy}{dx}x + y^2 = 0

Step 2: Simplify to isolate dydx\frac{dy}{dx}

Reorganize terms: 2xy+x2dydx+2xydydx+y2=02xy + x^2\frac{dy}{dx} + 2xy\frac{dy}{dx} + y^2 = 0 Group terms involving dydx\frac{dy}{dx}: x2dydx+2xydydx=2xyy2x^2\frac{dy}{dx} + 2xy\frac{dy}{dx} = -2xy - y^2 Factor dydx\frac{dy}{dx}: dydx(x2+2xy)=2xyy2\frac{dy}{dx}(x^2 + 2xy) = -2xy - y^2 Solve for dydx\frac{dy}{dx}: dydx=2xyy2x2+2xy\frac{dy}{dx} = \frac{-2xy - y^2}{x^2 + 2xy}


Summary of Results

  1. Slope of the tangent line for Problem 1: 511\boxed{-\frac{5}{11}}
  2. Expression for dydx\frac{dy}{dx} in Problem 2: 2xyy2x2+2xy\boxed{\frac{-2xy - y^2}{x^2 + 2xy}}

Let me know if you’d like further explanations or clarifications!


Related Questions

  1. How does implicit differentiation work when both xx and yy are involved in products?
  2. Can the slope of a tangent line be interpreted geometrically for these problems?
  3. How would the slope change if the point in Problem 1 were different?
  4. Could Problem 2 involve any critical points for yy (e.g., dydx=0\frac{dy}{dx} = 0)?
  5. How does the product rule simplify differentiation in these scenarios?

Tip: Always isolate dydx\frac{dy}{dx} systematically by factoring and reorganizing terms to avoid algebraic errors.

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Math Problem Analysis

Mathematical Concepts

Implicit Differentiation
Algebraic Manipulation
Calculus - Derivatives

Formulas

Product Rule: d(uv)/dx = u'v + uv'
Chain Rule: d/dx[f(y)] = f'(y) * dy/dx
General Differentiation Rules

Theorems

Implicit Differentiation Technique

Suitable Grade Level

Grades 10-12