Math Problem Statement

Assume that 2x + 3y = 12 and dy/dt = -2. Find dx/dt.

Solution

The given equation is 2x+3y=122x + 3y = 12, and you are asked to find dxdt\frac{dx}{dt} given that dydt=2\frac{dy}{dt} = -2.

To solve this, we will implicitly differentiate both sides of the equation with respect to tt.

Step 1: Differentiate 2x+3y=122x + 3y = 12

  • The derivative of 2x2x with respect to tt is 2dxdt2 \frac{dx}{dt} (using the chain rule).
  • The derivative of 3y3y with respect to tt is 3dydt3 \frac{dy}{dt} (also using the chain rule).
  • The derivative of the constant 1212 is 0.

So, differentiating both sides of the equation:

ddt(2x+3y)=ddt(12)\frac{d}{dt}(2x + 3y) = \frac{d}{dt}(12)

2dxdt+3dydt=02 \frac{dx}{dt} + 3 \frac{dy}{dt} = 0

Step 2: Substitute the given value dydt=2\frac{dy}{dt} = -2

2dxdt+3(2)=02 \frac{dx}{dt} + 3(-2) = 0

Simplifying:

2dxdt6=02 \frac{dx}{dt} - 6 = 0

Step 3: Solve for dxdt\frac{dx}{dt}

2dxdt=62 \frac{dx}{dt} = 6

dxdt=62=3\frac{dx}{dt} = \frac{6}{2} = 3

Final Answer:

dxdt=3\frac{dx}{dt} = 3

Would you like further details on this? Here are a few related questions to expand on this concept:

  1. How do you apply implicit differentiation to functions of multiple variables?
  2. What is the chain rule, and how is it used in this context?
  3. Can you explain how to differentiate implicit equations with respect to time in general?
  4. What does the result dxdt=3\frac{dx}{dt} = 3 mean in practical terms?
  5. How would the solution change if dydt\frac{dy}{dt} were positive instead of negative?

Tip: Always remember to apply the chain rule when differentiating variables that depend on another variable like time tt.

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Math Problem Analysis

Mathematical Concepts

Implicit Differentiation
Chain Rule
Algebra

Formulas

2x + 3y = 12
d/dt(2x + 3y) = 0
Chain Rule: d/dt(x) = dx/dt

Theorems

Chain Rule

Suitable Grade Level

Grades 11-12 (Calculus Level)