Math Problem Statement

Find the polynomial of the specified degree whose graph is shown. Degree 4.

Solution

The graph provided shows a degree 4 polynomial with certain characteristics, such as intercepts and turning points. To determine the equation of the polynomial, we can use the x-intercepts (roots) and general structure of a degree 4 polynomial.

Observations:

  1. Degree: The polynomial is of degree 4, meaning its general form will be: P(x)=a(xr1)(xr2)(xr3)(xr4)P(x) = a(x - r_1)(x - r_2)(x - r_3)(x - r_4) where r1,r2,r3,r4r_1, r_2, r_3, r_4 are the roots and aa is a constant scaling factor.

  2. Roots (x-intercepts): From the graph, the polynomial crosses the x-axis at x=3x = -3, x=1x = 1, and touches (but doesn't cross) at x=0x = 0 (indicating a double root).

    • The roots are x=3x = -3, x=0x = 0 (with multiplicity 2), and x=1x = 1.

Thus, the polynomial can be written as: P(x)=a(x+3)(x)2(x1)P(x) = a(x + 3)(x)^2(x - 1)

  1. Coefficient aa: To find the scaling factor aa, we can use a point on the graph, such as the y-intercept, which is given at P(0)=0P(0) = 0, so we need a different point. For example, at x=2x = -2, the approximate value of yy seems to be about P(2)8P(-2) \approx 8.

Let's solve using this approximation: P(2)=a(2+3)(2)2(21)=a(1)(4)(3)=12aP(-2) = a(-2 + 3)(-2)^2(-2 - 1) = a(1)(4)(-3) = -12a Given that P(2)8P(-2) \approx 8, we set up the equation: 12a=8    a=23-12a = 8 \implies a = -\frac{2}{3}

Final Polynomial:

P(x)=23(x+3)x2(x1)P(x) = -\frac{2}{3}(x + 3)x^2(x - 1)

Let me know if you'd like to go into more detail, check the calculation, or if you have other questions.

Follow-up questions:

  1. How do the multiplicities of roots affect the graph's behavior at intercepts?
  2. Why does the graph touch the x-axis at x=0x = 0 but crosses it at other points?
  3. How can we use more precise points on the graph to improve accuracy in the constant aa?
  4. What would happen to the shape of the graph if the polynomial degree increased or decreased?
  5. Could we use another method, such as fitting a polynomial through points, to verify this equation?

Tip:

Whenever determining polynomials from graphs, always observe the roots, behavior at intercepts, and use known points to determine the leading coefficient for accurate modeling.

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Math Problem Analysis

Mathematical Concepts

Polynomial Functions
Algebra
Graph Analysis

Formulas

General form of a degree 4 polynomial: P(x) = ax^4 + bx^3 + cx^2 + dx + e
Root (Zero) Theorem
Factorization

Theorems

Fundamental Theorem of Algebra
Multiplicity of Roots Theorem

Suitable Grade Level

Grades 11-12