Math Problem Statement

Let G = 4f - g, where the graphs of f and g are shown in the figure. Find G'(1).

Solution

We are given that G(x)=4f(x)g(x)G(x) = 4f(x) - g(x), where f(x)f(x) and g(x)g(x) are shown in the graph, and we need to find G(1)G'(1), which is the derivative of G(x)G(x) at x=1x = 1.

Step-by-step solution:

  1. Derivative of G(x): G(x)=ddx[4f(x)g(x)]=4f(x)g(x)G'(x) = \frac{d}{dx} [4f(x) - g(x)] = 4f'(x) - g'(x) So, to find G(1)G'(1), we need to calculate f(1)f'(1) and g(1)g'(1), the derivatives of f(x)f(x) and g(x)g(x) at x=1x = 1.

  2. Determine slopes from the graph: The derivative at a point is the slope of the tangent line at that point. From the graph, we can estimate the slopes of f(x)f(x) and g(x)g(x) at x=1x = 1.

    • The function f(x)f(x) appears to be a straight line with a positive slope in the segment where x=1x = 1. We can calculate the slope by observing the rise over run between two points on this line.

      For f(x)f(x):

      • Between (0,2)(0, 2) and (2,4)(2, 4), the slope is: f(x)=4220=22=1f'(x) = \frac{4 - 2}{2 - 0} = \frac{2}{2} = 1 So, f(1)=1f'(1) = 1.
    • The function g(x)g(x) also appears linear in the segment where x=1x = 1. From the graph, we observe:

      For g(x)g(x):

      • Between (0,0)(0, 0) and (2,4)(2, 4), the slope is: g(x)=4020=42=2g'(x) = \frac{4 - 0}{2 - 0} = \frac{4}{2} = 2 So, g(1)=2g'(1) = 2.
  3. Calculate G(1)G'(1): Now that we have f(1)=1f'(1) = 1 and g(1)=2g'(1) = 2, we can substitute into the expression for G(x)G'(x): G(1)=4f(1)g(1)=4(1)2=42=2G'(1) = 4f'(1) - g'(1) = 4(1) - 2 = 4 - 2 = 2

Final Answer:

G(1)=2G'(1) = 2

Would you like further details on any step, or have any questions about this solution?

Here are five related questions to explore:

  1. How do you find the derivative of a function from a graph if the function is not linear?
  2. What is the geometric interpretation of the derivative at a point?
  3. How do we differentiate a product of functions?
  4. Can the second derivative give us more information about the graph's behavior at x=1x = 1?
  5. How do you compute the derivative of a composite function?

Tip: When interpreting graphs, remember that the steeper the line, the larger the magnitude of the derivative.

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Math Problem Analysis

Mathematical Concepts

Derivative
Graphical Interpretation of Functions
Linear Functions

Formulas

G'(x) = 4f'(x) - g'(x)

Theorems

Slope of a Line
First Derivative

Suitable Grade Level

Grades 10-12