Math Problem Statement

Find an equation of the tangent line to the graph of the function y = (2x - 3) / (2x + 3) at the point (3, 1/3).

Solution

The problem is asking for the equation of the tangent line to the graph of the function y=2x32x+3y = \frac{2x - 3}{2x + 3} at the point (3,13)\left( 3, \frac{1}{3} \right).

Steps to solve:

  1. Find the derivative yy' (slope of the tangent line) using the quotient rule, which is: ddx(f(x)g(x))=f(x)g(x)f(x)g(x)g(x)2\frac{d}{dx} \left( \frac{f(x)}{g(x)} \right) = \frac{f'(x)g(x) - f(x)g'(x)}{g(x)^2} Here, f(x)=2x3f(x) = 2x - 3 and g(x)=2x+3g(x) = 2x + 3.

    Compute:

    • f(x)=2f'(x) = 2
    • g(x)=2g'(x) = 2

    Applying the quotient rule: y=(2)(2x+3)(2x3)(2)(2x+3)2y' = \frac{(2)(2x + 3) - (2x - 3)(2)}{(2x + 3)^2} Simplify:

    = \frac{4x + 6 - 4x + 6}{(2x + 3)^2} = \frac{12}{(2x + 3)^2}$$
  2. Evaluate the slope at x=3x = 3: y(3)=12(2(3)+3)2=12(6+3)2=1292=1281=427y'(3) = \frac{12}{(2(3) + 3)^2} = \frac{12}{(6 + 3)^2} = \frac{12}{9^2} = \frac{12}{81} = \frac{4}{27}

    The slope of the tangent line at x=3x = 3 is 427\frac{4}{27}.

  3. Use the point-slope form of the line equation: yy1=m(xx1)y - y_1 = m(x - x_1) where m=427m = \frac{4}{27}, x1=3x_1 = 3, and y1=13y_1 = \frac{1}{3}.

    Substitute: y13=427(x3)y - \frac{1}{3} = \frac{4}{27}(x - 3)

  4. Solve for yy: y=427(x3)+13y = \frac{4}{27}(x - 3) + \frac{1}{3}

Thus, the equation of the tangent line is: y=427(x3)+13y = \frac{4}{27}(x - 3) + \frac{1}{3}

The correct option is the first one:

y=427(x3)+13y = \frac{4}{27}(x - 3) + \frac{1}{3}

Would you like further details on any of these steps?

Here are 5 related questions for practice:

  1. How do you use the quotient rule in differentiation?
  2. What is the formula for the point-slope form of a line?
  3. How do you calculate the derivative of a rational function?
  4. Why is the slope of a tangent line equal to the derivative at a point?
  5. How can you find the tangent line for more complex functions?

Tip: The quotient rule is key when differentiating functions expressed as one function divided by another!

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Math Problem Analysis

Mathematical Concepts

Calculus
Quotient Rule
Tangent Line
Derivatives

Formulas

Quotient Rule: (f'(x)g(x) - f(x)g'(x)) / g(x)^2
Point-Slope Form: y - y1 = m(x - x1)

Theorems

Quotient Rule for Differentiation

Suitable Grade Level

Grades 11-12 (or Calculus Level)