Math Problem Statement

solve the question

Assume that x = x(t) and y = y(t). Let y = x^3 + 4 and dx/dt = 2 when x = 5. Find dy/dt when x = 5.

Solution

We are given:

  • y=x3+4y = x^3 + 4
  • dxdt=2\frac{dx}{dt} = 2 when x=5x = 5

We are asked to find dydt\frac{dy}{dt} when x=5x = 5.

Solution:

To find dydt\frac{dy}{dt}, we can use the chain rule, which states: dydt=dydxdxdt\frac{dy}{dt} = \frac{dy}{dx} \cdot \frac{dx}{dt}

First, calculate dydx\frac{dy}{dx}: y=x3+4y = x^3 + 4 dydx=3x2\frac{dy}{dx} = 3x^2

Now, substitute x=5x = 5 into dydx\frac{dy}{dx}: dydx=3(5)2=3×25=75\frac{dy}{dx} = 3(5)^2 = 3 \times 25 = 75

Now, using the fact that dxdt=2\frac{dx}{dt} = 2, we find dydt\frac{dy}{dt}: dydt=75×2=150\frac{dy}{dt} = 75 \times 2 = 150

Thus, dydt=150\frac{dy}{dt} = 150 when x=5x = 5.

Let me know if you want further details or have questions!

Here are 5 related questions:

  1. How does the chain rule apply to implicit differentiation?
  2. What are some real-world applications of related rates problems like this one?
  3. How does the rate of change of xx affect the rate of change of yy?
  4. What is the general formula for differentiating a power of xx?
  5. Can you explain how the product rule would work if yy were a product of two functions?

Tip: Always ensure that when applying the chain rule, you correctly differentiate with respect to the intermediate variable and then multiply by its rate of change with respect to time.

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Math Problem Analysis

Mathematical Concepts

Differentiation
Related Rates
Chain Rule

Formulas

y = x^3 + 4
dy/dt = (dy/dx) * (dx/dt)
dy/dx = 3x^2

Theorems

Chain Rule

Suitable Grade Level

Grades 10-12