Math Problem Statement

Assuming that the equation defines x and y implicitly as differentiable functions xequals​f(t), yequals​g(t), find the slope of the curve xequals​f(t), yequals​g(t) at the given value of t. x cubed plus 2 t squaredequals19​, 2 y cubed minus 2 t squaredequals36​, tequals3

Solution

To find the slope of the curve defined by the implicit equations at the given value t=3t = 3, we need to implicitly differentiate both equations with respect to tt and then calculate the slope as dydx\frac{dy}{dx}.

The given equations are:

  1. x3+2t2=19x^3 + 2t^2 = 19
  2. 2y32t2=362y^3 - 2t^2 = 36

Step 1: Differentiate both equations with respect to tt.

For the first equation x3+2t2=19x^3 + 2t^2 = 19:

Differentiate implicitly with respect to tt:

ddt(x3)+ddt(2t2)=ddt(19)\frac{d}{dt}(x^3) + \frac{d}{dt}(2t^2) = \frac{d}{dt}(19)

This gives:

3x2dxdt+4t=03x^2 \frac{dx}{dt} + 4t = 0

So,

3x2dxdt=4t3x^2 \frac{dx}{dt} = -4t

Solving for dxdt\frac{dx}{dt}:

dxdt=4t3x2\frac{dx}{dt} = \frac{-4t}{3x^2}

For the second equation 2y32t2=362y^3 - 2t^2 = 36:

Differentiate implicitly with respect to tt:

23y2dydtddt(2t2)=02 \cdot 3y^2 \frac{dy}{dt} - \frac{d}{dt}(2t^2) = 0

This simplifies to:

6y2dydt4t=06y^2 \frac{dy}{dt} - 4t = 0

Solving for dydt\frac{dy}{dt}:

6y2dydt=4t6y^2 \frac{dy}{dt} = 4t

dydt=4t6y2=2t3y2\frac{dy}{dt} = \frac{4t}{6y^2} = \frac{2t}{3y^2}

Step 2: Evaluate at t=3t = 3.

We need to find xx and yy at t=3t = 3 by solving the original equations.

First equation: x3+2t2=19x^3 + 2t^2 = 19

Substitute t=3t = 3:

x3+2(32)=19x^3 + 2(3^2) = 19

x3+18=19x^3 + 18 = 19

x3=1x^3 = 1

x=1x = 1

Second equation: 2y32t2=362y^3 - 2t^2 = 36

Substitute t=3t = 3:

2y32(32)=362y^3 - 2(3^2) = 36

2y318=362y^3 - 18 = 36

2y3=542y^3 = 54

y3=27y^3 = 27

y=3y = 3

Step 3: Calculate dxdt\frac{dx}{dt} and dydt\frac{dy}{dt} at t=3t = 3.

Using x=1x = 1 and y=3y = 3:

dxdt=4(3)3(1)2=123=4\frac{dx}{dt} = \frac{-4(3)}{3(1)^2} = \frac{-12}{3} = -4

dydt=2(3)3(32)=63(9)=627=29\frac{dy}{dt} = \frac{2(3)}{3(3^2)} = \frac{6}{3(9)} = \frac{6}{27} = \frac{2}{9}

Step 4: Find the slope dydx\frac{dy}{dx}.

The slope of the curve is given by:

dydx=dydtdxdt=294=29×14=236=118\frac{dy}{dx} = \frac{\frac{dy}{dt}}{\frac{dx}{dt}} = \frac{\frac{2}{9}}{-4} = \frac{2}{9} \times \frac{1}{-4} = \frac{-2}{36} = \frac{-1}{18}

Final Answer:

The slope of the curve at t=3t = 3 is 118\boxed{-\frac{1}{18}}.

Would you like any more details on this process or have questions? Here are some related questions to deepen your understanding:

  1. What is implicit differentiation, and why is it used here?
  2. How can you verify the results of implicit differentiation using numerical methods?
  3. How does the concept of parametric differentiation apply to this problem?
  4. What are some real-life applications of finding the slope of a curve defined implicitly?
  5. How would the problem change if higher-order derivatives were required?

Tip: When working with implicit differentiation, always remember to differentiate both sides of the equation with respect to the independent variable, keeping in mind the chain rule.

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Math Problem Analysis

Mathematical Concepts

Implicit Differentiation
Parametric Differentiation
Calculus
Algebra

Formulas

Implicit differentiation of x^3 + 2t^2 = 19: 3x^2 * (dx/dt) + 4t = 0
Implicit differentiation of 2y^3 - 2t^2 = 36: 6y^2 * (dy/dt) - 4t = 0
Slope of curve: dy/dx = (dy/dt) / (dx/dt)

Theorems

Chain Rule
Implicit Function Theorem

Suitable Grade Level

Grades 11-12, University Calculus Level