Solving Square Area, Function Inverses, and Rational Functions Explained

Question 1: Square Area as a Function of Perimeter

Given Function

  • Area function: A(P) = P2 / 16, where P ≥ 0 (P is the perimeter of the square).
  • Graph is considered for 0 ≤ P ≤ 20.

Part A: Calculate A(20) and A−1(12)

  • Calculate A(20):
    • Substitute P = 20 into A(P): (20)2 / 16 = 400 / 16 = 25.
  • Find inverse A−1(12):
    • Solve A(P) = 12 → P2 / 16 = 12 → P2 = 192 → P ≈ 13.9.
    • Thus, A−1(12) = 13.9.

Part B: Graphing the Inverse Function

  • Draw the line y = x as a reference.
  • Use points from the original function, e.g., (8,4), and switch coordinates to (4,8) for the inverse.
  • Plot these points and sketch the inverse curve.

Part C: Interpretation of Inverse

  • A−1(4) = 8 means a square with area 4 has a perimeter of 8.

Question 2: Function with Square Root

Given Function

  • f(x) = 7 - 4√(x + 5).

Domain and Range

  • Domain: x + 5 ≥ 0 → x ≥ -5.
  • Range: Since the square root is non-negative and multiplied by -4, the maximum value of f(x) is 7 (when x = -5).
  • Therefore, range is y ≤ 7.

Finding Inverse Value

  • Find f−1(2):
    • Set f(x) = 2 → 7 - 4√(x + 5) = 2.
    • Solve for x using calculator or algebra: x ≈ 3.5.

Question 3: Rational Function Analysis

Given Function

  • G(x) = 1 - 3 / (1 - a x).

Part A: Find a given point (2,2)

  • Substitute x=2, G(2)=2:
    • 2 = 1 - 3 / (1 - 2a).
    • Solve for a: a = 2.
  • Updated function: G(x) = 1 - 3 / (1 - 2x).

Part B: Domain and Vertical Asymptote

  • Denominator ≠ 0 → 1 - 2x ≠ 0 → x ≠ 1/2.
  • Vertical asymptote at x = 1/2.

Part C: Intercepts

  • X-intercept (G(x) = 0):
    • 0 = 1 - 3 / (1 - 2x) → solve for x → x = -1.
  • Y-intercept (x=0):
    • G(0) = 1 - 3 / 1 = -2.

Part D: Evaluate G(5) and G−1(5)

  • G(5):
    • G(5) = 1 - 3 / (1 - 2*5) = 1 - 3 / (1 - 10) = 1 - 3 / (-9) = 1 + 1/3 = 4/3 ≈ 1.33.
  • Find G−1(5):
    • Set G(x) = 5 → 1 - 3 / (1 - 2x) = 5.
    • Solve for x → x = 0.25.

Summary

This content demonstrates how to:

  • Calculate function values and inverses for quadratic and square root functions.
  • Graph inverse functions by reflecting points across y = x.
  • Determine domain, range, and vertical asymptotes for rational functions.
  • Find intercepts and solve for unknown parameters using given points.
  • Use calculators effectively to solve equations and verify results.

These techniques are essential for understanding function behavior and solving real-world mathematical problems involving geometry and algebra.

For further reading on related topics, check out these guides:

Keep this summary

Save it to LunaNotes and it becomes a real note in your library — editable, searchable, and ready to turn into flashcards or a diagram. Free to start.

Save to LunaNotes

Or summarise for another video.

This summary and transcript were automatically generated using AI with the Free YouTube Transcript Summary Tool by LunaNotes.

Found this summary useful?

Take it with you. One click puts it in your own LunaNotes library.

Save to LunaNotes

Start taking better notes today with LunaNotes