C++ function with multiple defaulted parameters used as a polynomial: compute two outputs for x = 2.3.\n\n#include <iostream.h>\n\ndouble CuriousTabFunction(double, double, double = 0, double = 0, double = 0);\n\nint main()\n{\n double d = 2.3;\n cout << CuriousTabFunction(d, 7) << " ";\n cout << CuriousTabFunction(d, 7, 6) << endl;\n return 0;\n}\n\ndouble CuriousTabFunction(double x, double p, double q, double r, double s)\n{\n return p + (q + (r + s * x) * x) * x; // Horner-like form\n}\n

Difficulty: Easy

Correct Answer: 7 20.8

Explanation:


Introduction / Context:
The function evaluates a cubic-like expression using Horner-style nesting. Default arguments make most coefficients zero unless explicitly provided. You must track which parameters receive values and which default to zero.



Given Data / Assumptions:

  • x = 2.3.
  • First call: p = 7, q = r = s = 0.
  • Second call: p = 7, q = 6, r = s = 0.


Concept / Approach:
For the first call, every nested term beyond p cancels to zero, leaving p. For the second call, only q contributes beyond p, scaled by x once. Evaluating carefully yields numeric results.



Step-by-Step Solution:

Call 1: p + (q + (r + sx)x)x with q=r=s=0 → 7 + (0 + (0 + 0)x)x = 7.Call 2: p=7, q=6, r=s=0 → 7 + (6 + (0 + 0)x)x = 7 + 6x = 7 + 62.3 = 7 + 13.8 = 20.8.


Verification / Alternative check:
Writing the general form as p + qx + rx^2 + sx^3 confirms that only qx contributes in the second call.



Why Other Options Are Wrong:

  • 7 20: Misses the 0.8 contribution of 60.133..; numerically incorrect.
  • 7 19.8: Off by 1.0; likely mistaken sign.
  • 7 Garbage / None of the above: All arguments are defined and the math is straightforward.


Common Pitfalls:
Misplacing parentheses in nested expressions, or forgetting that only q survives when r and s are zero.



Final Answer:
7 20.8

More Questions from Functions

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion