Math Problem Statement

Let a and b be real numbers where a ≠ b ≠ 0. Which of the following functions could represent the graph below?

Solution

Let's analyze the given graph and the function options to identify the correct one.

Observing the Graph:

  • The graph appears to have three distinct x-intercepts: one at x=0x = 0, and two others at points x=ax = a and x=bx = b, where aa and bb are different from 0.
  • It has a double root at both x=ax = a and x=bx = b, meaning the graph touches the x-axis at these points without crossing it. This suggests that the factors (xa)(x - a) and (xb)(x - b) should be squared.
  • Additionally, the graph crosses the x-axis at x=0x = 0, implying xx is a factor.
  • The shape of the graph shows that it behaves like a cubic function at x=0x = 0, as it crosses the x-axis rather sharply, indicating an odd multiplicity.

Evaluating the Options:

  1. f(x)=x(xa)3(xb)3f(x) = x(x - a)^3(x - b)^3: This would have the graph crossing the x-axis at x=ax = a and x=bx = b due to the odd powers (3), but the graph only touches these points, not crosses them, so this is incorrect.

  2. f(x)=(xa)2(xb)4f(x) = (x - a)^2(x - b)^4: There is no factor for x=0x = 0, so this is incorrect since the graph crosses the x-axis at x=0x = 0.

  3. f(x)=x(xa)6(xb)2f(x) = x(x - a)^6(x - b)^2: While this includes the x=0x = 0 factor, the powers of 6 and 2 are too large for the behavior seen at x=ax = a and x=bx = b, which would make the graph flatter than it appears.

  4. f(x)=x(xa)5(xb)2f(x) = x(x - a)^5(x - b)^2: This fits the criteria:

    • xx is a factor, meaning the graph crosses the x-axis at x=0x = 0.
    • The factor (xa)5(x - a)^5 means the graph behaves like a cubic near x=ax = a but with an odd multiplicity (the graph crosses or changes direction), matching the behavior at x=ax = a.
    • The factor (xb)2(x - b)^2 gives a double root, which matches the graph touching but not crossing the x-axis at x=bx = b.

Conclusion:

The correct function is f(x)=x(xa)5(xb)2f(x) = x(x - a)^5(x - b)^2, which is the last option.

Let me know if you need more details or have questions! Here are some related questions:

  1. What is the significance of the multiplicity of roots in a polynomial function's graph?
  2. How can we determine the degree of a polynomial from its graph?
  3. What happens to the shape of the graph as the degree of a factor increases?
  4. How do odd and even multiplicities affect how a graph crosses the x-axis?
  5. Can a polynomial have multiple roots at the same x-value?

Tip: The multiplicity of a root directly affects how the graph behaves at that x-value—odd multiplicities result in the graph crossing the axis, while even multiplicities cause it to touch the axis but not cross.

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Math Problem Analysis

Mathematical Concepts

Polynomial functions
Graph behavior of polynomials
Root multiplicity

Formulas

Factorization of polynomial functions f(x) = (x - a)^n(x - b)^m
Roots and multiplicity relationship to graph behavior

Theorems

Multiplicity of polynomial roots
Odd vs. even multiplicity behavior

Suitable Grade Level

Grades 10-12